#help-0 | Mathematics | Page 705

shadow edge Jul 12, 2021, 9:43 PM

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plus im in summer school and the teacher does not give notes

glass lichen Jul 12, 2021, 9:43 PM

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You make your own notes

shadow edge Jul 12, 2021, 9:43 PM

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i bought a calculus book so thats my stuff

glass lichen Jul 12, 2021, 9:44 PM

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then look at the appendix and see if it has implicit....

sour pasture Jul 12, 2021, 9:44 PM

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@shadow edge
If i were to ask you "Compute d/dx of (x^2) sin(2x) " how would you answer?

shadow edge Jul 12, 2021, 9:45 PM

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derivate x^2 then sin2x

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so i would do 2x

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cos2x d/dx (2x)

sour pasture Jul 12, 2021, 9:52 PM

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@shadow edge
Don't worry about it mate.
So we want to take d/dx of (x^2) sin(2x).

You're right in that eventually we'll need to differentiate the little dudes,
but to differentiate a product remember it's not the product of derivatives, it's not the sum of derivatives -- it follows some other logic.

Would you agree it's :
(d/dx of x^2) sin(2x) + x^2 (d/dx of sin(2x)) ?

Then resolving it all gives:
2xsin(2x) + 2x^2cos(2x).

Makes sense?

shadow edge Jul 12, 2021, 9:53 PM

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yea

sour pasture Jul 12, 2021, 9:54 PM

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@shadow edge Okay cool,
So you now suppose I asked you "Compute d/dx of (x^3) sin(2x) " how would you answer? (give the final answer)

shadow edge Jul 12, 2021, 9:55 PM

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(x^3)' sin(2x) + x^3 (sin(2x))'

sour pasture Jul 12, 2021, 9:55 PM

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perfect

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So now what if i give you:

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"Compute d/dx of (y) sin(2x) " how would you answer?
y is some unkown, unspecified, mysterious function of x.
Pretend all the niceities in life.
pretend it can be differentiated.
it's just some other function like x^2, like x^3.
But without knowing its explicit form, knowing only its name how would you respond?

shadow edge Jul 12, 2021, 9:58 PM

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so basically i just have to derivate the two sides separate?

ionic jewel Jul 12, 2021, 9:59 PM

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though that was a question

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mb

sour pasture Jul 12, 2021, 10:05 PM

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@shadow edge
When asked the question "Compute d/dx of (x^2) sin(2x) ",
you answered correctly: (d/dx of x^2) sin(2x) + x^2 (d/dx of sin(2x)).

When asked "Compute d/dx of (x^3) sin(2x) ",
you again answered : (d/dx of x^3) sin(2x) + x^3 (d/dx of sin(2x)).

So now when confronted with the unknown "Compute d/dx of (y) sin(2x) ",
fear not. For you have already answered all the questions before it.
Not knowing what y is, but knowing that it's one of the functions for which we have already answered the question, we can safely say (just as Bunny said by product rule) that
the answer is: (d/dx of y) sin(2x) + y (d/dx of sin(2x)).

It's simply dy/dx sin (2x) + 2ycos(2x).
Remember that dy/dx is not a constant wrt differentiation, but the slope of the tangent at (x,y).

shell narwhal Jul 12, 2021, 10:07 PM

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what is the difference between dy/dx and d/dx ?

sour pasture Jul 12, 2021, 10:08 PM

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shell narwhal what is the difference between dy/dx and d/dx ?

by d/dx one means the operation of differentiating.
by dy/dx one means particularly differentiating y.

shell narwhal Jul 12, 2021, 10:08 PM

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oh ok

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so almost the same thing

shadow edge Jul 12, 2021, 10:12 PM

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@sour pasture So from what I understand, I have to derivate both sides separateley and replace the variables with the points from the graph. That will give me the slope so I can find the tangent eqation. Is my thinking ok?

sour pasture Jul 12, 2021, 10:14 PM

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shadow edge <@!143225879110090752> So from what I understand, I have to derivate both sides ...

yeah you differentiate both sides, and do this product rule (because y is some function of x), and just like how are lhs contains x's y's and dy/dx's,
the rhs will contain x's, y's, and dy/dx's.
You can essentially solve for dy/dx or give the problem to an underclassman.

shadow edge Jul 12, 2021, 10:15 PM

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Thanks so much.

shell narwhal Jul 12, 2021, 10:19 PM

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so you will end up with something = something ?

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ex: 3 = 3 ?

alpine sable Jul 12, 2021, 10:19 PM

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whats the formula to work out what p will be

shell narwhal Jul 12, 2021, 10:20 PM

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sour pasture yeah you differentiate both sides, and do this product rule (because y is some f...

am i right ?

sour pasture Jul 12, 2021, 10:21 PM

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shell narwhal am i right ?

i think so. yes.

shell narwhal Jul 12, 2021, 10:21 PM

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ok thx ur the best

alpine sable Jul 12, 2021, 10:21 PM

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sour pasture i think so. yes.

can you help me out

sour pasture Jul 12, 2021, 10:23 PM

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alpine sable can you help me out

Sorry :(. My time here is up.

alpine sable Jul 12, 2021, 10:24 PM

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farewell

warped phoenix Jul 12, 2021, 10:38 PM

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What do they mean by symmetric about the origin?

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I was told that if it was even, it would be reflecting across the y-axis, and if it was odd, then it would be passing through the origin, and if it was flipped upside down it would "match"

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i wasnt exactly sure what they meant by match

glacial hedge Jul 12, 2021, 10:43 PM

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warped phoenix What do they mean by symmetric about the origin?

symetric by the origin is a fancy way of saying f(-x) = -f(x)

alpine sable Jul 12, 2021, 10:43 PM

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glacial hedge symetric by the origin is a fancy way of saying f(-x) = -f(x)

can you help me out?

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peak storm Jul 12, 2021, 10:46 PM

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<@&286206848099549185>

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Pls help me

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Is question 13 up to the far right?

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??

glacial hedge Jul 12, 2021, 10:47 PM

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alpine sable can you help me out?

yeah

glacial hedge Jul 12, 2021, 10:55 PM

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alpine sable can you help me out?

parceni still need help?

rugged ermine Jul 12, 2021, 11:05 PM

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i have a hoorrible problem

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but 0 idea how to solve it after factoring out

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ill send it rn

glacial tiger Jul 12, 2021, 11:07 PM

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hey can anyone help?

rugged ermine Jul 12, 2021, 11:15 PM

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,help

ocean sealBOT Jul 12, 2021, 11:15 PM

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A brief description and guide on how to use me was sent to your DMs!
Please use ,list to see a list of all my commands, and ,help cmd to get detailed help on a command!

glass lichen Jul 12, 2021, 11:23 PM

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warped phoenix What do they mean by symmetric about the origin?

rotationally symmetric about the origin by 180 degrees is odd symmetry

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not a reflection

neon moss Jul 13, 2021, 12:10 AM

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what trig identities makes this so

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i can't think of a way sin(x) + cos(x) * ∆t == sin(x + ∆t)

glacial hedge Jul 13, 2021, 12:10 AM

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neon moss

maybe the angle addition identities?

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wait nvm

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xD

neon moss Jul 13, 2021, 12:12 AM

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cant be :/

glacial hedge Jul 13, 2021, 12:13 AM

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that doesn't really make sense ur left with

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$sin(x+\deltat) = sin(x)+\deltatcos(x)$

ocean sealBOT Jul 13, 2021, 12:13 AM

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Elonmosqito96
Compile Error! Click the errors reaction for more information.
(You may edit your message to recompile.)

neon moss Jul 13, 2021, 12:19 AM

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hmm

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yeah idk

arctic wren Jul 13, 2021, 12:27 AM

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So..., most thing thing that humans invented, how humans behave has relation with math and normally what appear is pi, e, the golden ratio or prime numbers. I my experience pi normally appears in periods, the golden ratio with ratios , thus they can't appear, at my point of view on the stock market. Is there a relation between primes or e with the stock market ? If not exist a paper that dive into this though ?

quartz beacon Jul 13, 2021, 12:51 AM

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arctic wren So..., most thing thing that humans invented, how humans behave has relation wit...

this is interesting as fuck

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https://www.investopedia.com/articles/technical/04/033104.asp this might help you @arctic wren

Investopedia

Fibonacci and the Golden Ratio: Using Technical Analysis to Unlock ...

Discover how the amazing ratio, revealed in countless proportions throughout nature, applies to financial markets.

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aliás, tu é br e isso é mt foda

alpine sable Jul 13, 2021, 12:53 AM

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math is nature

vague coral Jul 13, 2021, 12:53 AM

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math is everywhere

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KawaiiTeri

alpine sable Jul 13, 2021, 12:53 AM

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even in my house??

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thats creepy

vague coral Jul 13, 2021, 12:53 AM

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yes

arctic umbra Jul 13, 2021, 1:03 AM

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ya

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n0 is 55572

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the growth rate is 0.05

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111144 is the number of cases that r doubled

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you have 111144=55572(1.05)^t

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solve

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you can simplify to 2=1.05^t

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then use logs

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easiest way is to use logs

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this is occupied rn

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but i can tell u after

golden wharf Jul 13, 2021, 1:07 AM

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Ok

arctic umbra Jul 13, 2021, 1:07 AM

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you get log 1.05 (2) = t

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and thats ur answer

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just plug everything in

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if its an equation and you have everything except one variable you just solve

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~isolate the variable~

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ya

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111144=55572(1.05)^t

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when u work with exponential growth

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u should understand the parts

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55572 always represents what u start off with

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logs

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no

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do you know what a log

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like is

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?

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like if u had

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2^x=5

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how would u solve it

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mm

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and u got ur answer

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think of the 1.05 as the base

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log 1.05 (2) = t

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yea

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wdym?

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just see it and u get log 1.05 (2)= t

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like if its 2^x = 5

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i know its the same as log 2 (5)=x

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there r parts of a log

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the base

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the exponent

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the answer (idrk what to call it)

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yea

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u mean after u get the log?

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did u work with logs before?

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thats all u gotta do

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a log is just the inverse of an exponent

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alpine sable Jul 13, 2021, 1:28 AM

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arctic umbra a log is just the inverse of an exponent

can you help me out

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pls

arctic umbra Jul 13, 2021, 1:29 AM

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mmk

alpine sable Jul 13, 2021, 1:29 AM

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I have this formula that gives me the number of years it takes a population to grow

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but each year there is an amount of new inhabitants

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how do I add on to it

arctic umbra Jul 13, 2021, 1:30 AM

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ok

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what variables r there

alpine sable Jul 13, 2021, 1:30 AM

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arctic umbra Jul 13, 2021, 1:30 AM

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ok

alpine sable Jul 13, 2021, 1:31 AM

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thats just an example

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I have to make a function that generates

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a time

arctic umbra Jul 13, 2021, 1:34 AM

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hmm

alpine sable Jul 13, 2021, 1:36 AM

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yeah but the part im stuck on is adding on to the new inhabitants

arctic umbra Jul 13, 2021, 1:36 AM

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i just useed exponents not natural logs but

alpine sable Jul 13, 2021, 1:37 AM

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ok

arctic umbra Jul 13, 2021, 1:38 AM

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instead of the one u put

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u could do 1000(1.02)^t

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i was gonna say 1000(1.02)^t+50t but that doesnt work

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wait yes it does

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does the 2 percent include the 50?

alpine sable Jul 13, 2021, 1:39 AM

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no

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arctic umbra Jul 13, 2021, 1:40 AM

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yea

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mine works

alpine sable Jul 13, 2021, 1:40 AM

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ok

arctic umbra Jul 13, 2021, 1:40 AM

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for the second year its 1140.4 not 1141

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so idk if mine isnt

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hold on

alpine sable Jul 13, 2021, 1:41 AM

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ok

arctic umbra Jul 13, 2021, 1:41 AM

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yea nvm mine dont work

shut tartan Jul 13, 2021, 1:41 AM

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hello how would i solve this

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Log2^x=3,7

arctic umbra Jul 13, 2021, 1:42 AM

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this is taken

shut tartan Jul 13, 2021, 1:42 AM

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oh ur taken?

arctic umbra Jul 13, 2021, 1:42 AM

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this channel -.-

alpine sable Jul 13, 2021, 1:42 AM

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shut tartan oh ur taken?

📸

shut tartan Jul 13, 2021, 1:42 AM

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aww that sucks u kind of cute

arctic umbra Jul 13, 2021, 1:42 AM

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🖐️anyways

ionic jewel Jul 13, 2021, 1:44 AM

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wow his username checks out

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he's down bad

arctic umbra Jul 13, 2021, 1:45 AM

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right

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my brain isnt working rn @alpine sable

shut tartan Jul 13, 2021, 1:45 AM

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ok stop bullying me

arctic umbra Jul 13, 2021, 1:45 AM

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idk im like not getting one

shut tartan Jul 13, 2021, 1:45 AM

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help me when u guys r done thanks😊

arctic umbra Jul 13, 2021, 1:46 AM

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is ur log 2^x in base ten

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or did u mean log 2 (x)

shut tartan Jul 13, 2021, 1:46 AM

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the answer is 12.906

shut tartan Jul 13, 2021, 1:47 AM

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arctic umbra is ur log 2^x in base ten

yes

alpine sable Jul 13, 2021, 1:48 AM

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arctic umbra my brain isnt working rn <@456226577798135808>

ok

arctic umbra Jul 13, 2021, 1:49 AM

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the 3,7 is supposed to be there

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right

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?

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how would u get multiple answers

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@shut tartan

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bruh... you meant to put log 2 (x)= 3.7

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i cant 🖐️

alpine sable Jul 13, 2021, 1:56 AM

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shut tartan aww that sucks u kind of cute

shut up

arctic umbra Jul 13, 2021, 1:56 AM

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its not base 10, 2 is the base

alpine sable Jul 13, 2021, 1:56 AM

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shut tartan Log2^x=3,7

You can rewrite the variable power od the log as the coefficient then put the log 2 as the base in the right hand side

arctic umbra Jul 13, 2021, 1:56 AM

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you just do 2^3.7= 12.996

alpine sable Jul 13, 2021, 1:57 AM

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Yeah

arctic umbra Jul 13, 2021, 1:57 AM

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alpine sable You can rewrite the variable power od the log as the coefficient then put the lo...

the base isnt 10 😮‍💨

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😦

alpine sable Jul 13, 2021, 1:57 AM

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2 is the base

arctic umbra Jul 13, 2021, 1:57 AM

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yea

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the comma got me good

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thought there were 2 solutions like ???

alpine sable Jul 13, 2021, 1:57 AM

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I was flummoxed for a while as well haha

arctic umbra Jul 13, 2021, 1:58 AM

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alpine sable shut up

?

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anyways

alpine sable Jul 13, 2021, 1:59 AM

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lmao

left echo Jul 13, 2021, 2:05 AM

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can somebody help me w this cus i’m getting the wrong answer and idk what i’m doing wrong

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the answer is supposed to be 2x^2 - x + 5 - 17/2x+1

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but how am i supposed to get 2x at the start when u just bring down the 4

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when u use synthetic division

dusk hearth Jul 13, 2021, 2:08 AM

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does anyone know how to solve this (btw it is substituting values into formula)

Screen_Shot_2021-07-13_at_12.08.05_pm.png

arctic umbra Jul 13, 2021, 2:11 AM

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someone already posted above you

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but u need more than that one equation if u have 2 variables

mint urchin Jul 13, 2021, 2:12 AM

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dusk hearth does anyone know how to solve this (btw it is substituting values into formula)

i dont think its possible to solve with the info youve given.

dusk hearth Jul 13, 2021, 2:13 AM

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ah ok, thanks for the help anyways

proper fern Jul 13, 2021, 2:15 AM

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@dusk hearth simply the answer is in terms of other variable here for example

5x-4y = 1
x = (1+4y)/5

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thats the solution

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you can then substitute x in equation and get value of y

mint urchin Jul 13, 2021, 2:23 AM

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wow youre right, i forgot you can solve it like this.

tacit mortar Jul 13, 2021, 2:26 AM

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hi

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i take channel

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ig

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for this question i got this as my answer $[-1 - \sqrt{3}, 0) \cup [\sqrt{3} - 1, \infty)$

ocean sealBOT Jul 13, 2021, 2:27 AM

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idkwhatnametoput

tacit mortar Jul 13, 2021, 2:27 AM

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Right or wrong

shut tartan Jul 13, 2021, 2:31 AM

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arctic umbra you just do 2^3.7= 12.996

omg im so dumb i could have jst converted it to exponential form and then 2^3.7 gives you 12.99

rigid smelt Jul 13, 2021, 2:34 AM

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,w 1/x - x/2 <=1

ocean sealBOT Jul 13, 2021, 2:34 AM

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quasi venture Jul 13, 2021, 2:34 AM

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can someone pls help, i've been stuck for ages

rigid smelt Jul 13, 2021, 2:34 AM

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tacit mortar Right or wrong

Seems right

tacit mortar Jul 13, 2021, 2:34 AM

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ty

rigid smelt Jul 13, 2021, 2:35 AM

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quasi venture can someone pls help, i've been stuck for ages

Write the square root as a power

quasi venture Jul 13, 2021, 2:39 AM

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so it would be (25xy^2) ^ 2

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?

rigid smelt Jul 13, 2021, 2:39 AM

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Yes

quasi venture Jul 13, 2021, 2:39 AM

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wait wouldn't it be 1/2 not 2?

rigid smelt Jul 13, 2021, 2:39 AM

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now apply every single expoenent rule you can remember

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Yesh 1/2

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You wrote

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Oh you wrote 2

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Oops

quasi venture Jul 13, 2021, 2:40 AM

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alright ill try it ty

peak tiger Jul 13, 2021, 2:41 AM

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can someone help me with (a)?

rigid smelt Jul 13, 2021, 2:41 AM

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What have you tried

peak tiger Jul 13, 2021, 2:42 AM

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I've tried subbing in 1 and 1+h into x

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it wasn't the answer though as I got like (-6+2h-2h^2)/h

rigid smelt Jul 13, 2021, 2:43 AM

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Thats wrong

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You have to apply the slope formula

peak tiger Jul 13, 2021, 2:43 AM

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(y2-y1)/(x2-x1)?

rigid smelt Jul 13, 2021, 2:43 AM

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Yes

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Where x_2 and x_1 is 1 and 1+h

peak tiger Jul 13, 2021, 2:44 AM

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that's what i've been doing

quasi venture Jul 13, 2021, 2:45 AM

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quasi venture can someone pls help, i've been stuck for ages

ive gotten to

25^(1/2) x^(1/2) y/ 4x^(2/3) y^-3

im stuck again sad

rigid smelt Jul 13, 2021, 2:46 AM

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Ok someone has to move now

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,w 6(1+h)- 2(1+h)^2

ocean sealBOT Jul 13, 2021, 2:47 AM

#

#

#

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Results provided by WolframAlpha

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rigid smelt Jul 13, 2021, 2:47 AM

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Yeah you didnt expand it correct or something

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You should get -2h^2 +2h +8

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For the numerator

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Check your work again

gaunt magnet Jul 13, 2021, 2:47 AM

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the answer i got
The function, F(x), is shown. State the intervals on which F(x) < 0

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correct?

rigid smelt Jul 13, 2021, 2:48 AM

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Channel is busy please move

gaunt magnet Jul 13, 2021, 2:49 AM

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😭

earnest rover Jul 13, 2021, 2:50 AM

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I have the following. I want to write an equation I just don't know how to put my idea down would like some input from yall fr.

So. We have P_1 = R(1-0.5) * 1.75^X
Where X is 2 weeks intervals.
However I want X to also change as this function continues!

I want 2 weeks to now become maybe 3 weeks to then become 4 weeks. And and on and on as P_1 grows.

gaunt magnet Jul 13, 2021, 2:50 AM

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LOL

earnest rover Jul 13, 2021, 2:50 AM

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Oops

rigid smelt Jul 13, 2021, 2:51 AM

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Bruh

gaunt magnet Jul 13, 2021, 3:10 AM

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gaunt magnet the answer i got The function, F(x), is shown. State the intervals on which F(x...

<@&286206848099549185>

dark granite Jul 13, 2021, 3:11 AM

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@gaunt magnet Your work looks good

gaunt magnet Jul 13, 2021, 3:13 AM

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dark granite <@!700774145365114920> Your work looks good

so the the intervals i stated are all correct for my question

dark granite Jul 13, 2021, 3:14 AM

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gaunt magnet so the the intervals i stated are all correct for my question

yes

gaunt magnet Jul 13, 2021, 3:14 AM

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ok then thanks

dark granite Jul 13, 2021, 3:18 AM

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You're welcome

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This channel is open for questions

glacial hedge Jul 13, 2021, 3:19 AM

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Could someone explain a theorem in linear algebra to me it doesn't really make sense

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if Set S is linearly dependant and indexed and v_1 != 0 then there is v_j (j >1) is a linear combination of the preceding vectors

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why does it have to be preceding vectors?

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and why does it have to be indexed?

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<@&286206848099549185> ?

gaunt magnet Jul 13, 2021, 3:50 AM

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Hi bunny

ionic jewel Jul 13, 2021, 3:50 AM

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glacial hedge if Set S is linearly dependant and indexed and v_1 != 0 then there is v_j (j >1)...

do you want a proof or do you not understand what it means?

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hi usman

tacit mortar Jul 13, 2021, 3:50 AM

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channel take

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taken or not?

glacial hedge Jul 13, 2021, 3:51 AM

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ionic jewel do you want a proof or do you not understand what it means?

I am just confused on why is has to be preceding vectors

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and what that means

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why cant it be the vectors after it in a set>

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?

ionic jewel Jul 13, 2021, 3:52 AM

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i mean thats probably also true

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just not what the theorem says

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basically if you go left to right on your linearly dependent vectors, eventually you will get to one that's a linear combination of all the previous ones

ionic jewel Jul 13, 2021, 3:53 AM

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glacial hedge why cant it be the vectors after it in a set>

i think this would be a lemma, if I'm thinking about it right it follows straightforward from the provided proof

glacial hedge Jul 13, 2021, 3:53 AM

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wait so we are saying that by using preceding vectors we are limiting the set?

ionic jewel Jul 13, 2021, 3:54 AM

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you are limiting what you need to check, yes

glacial hedge Jul 13, 2021, 3:54 AM

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Ok i'll aks my teacher xD

tacit mortar Jul 13, 2021, 3:54 AM

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i got 6 as the answer just say yes if im correct

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had to round to nearest minute

ionic jewel Jul 13, 2021, 3:55 AM

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,w -5 = 2t^2/(t+1)-15

ocean sealBOT Jul 13, 2021, 3:55 AM

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glacial hedge Jul 13, 2021, 3:55 AM

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it should be 6 minutes

tacit mortar Jul 13, 2021, 3:55 AM

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glacial hedge it should be 6 minutes

ye got that

glacial hedge Jul 13, 2021, 3:55 AM

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oh

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im blind

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i saw 5 xD

ionic jewel Jul 13, 2021, 3:56 AM

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t = 5.84, so yes

tacit mortar Jul 13, 2021, 3:56 AM

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ionic jewel t = 5.84, so yes

ye but u round it and get 6

ionic jewel Jul 13, 2021, 3:56 AM

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yep

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good job

glacial hedge Jul 13, 2021, 3:56 AM

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yep deez nutz

tacit mortar Jul 13, 2021, 3:58 AM

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Cross multiply
(X-6)²<=(x+2)²
x²+ 36 -12x<=x²+4+4x
32<=16x
2<=x

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got this correct?

ionic jewel Jul 13, 2021, 3:59 AM

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,w (x-6)/(x+2) <= (x+2)/(x-6)

ocean sealBOT Jul 13, 2021, 3:59 AM

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Results provided by WolframAlpha

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topaz scaffold Jul 13, 2021, 4:00 AM

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tacit mortar got this correct?

No...

tacit mortar Jul 13, 2021, 4:12 AM

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topaz scaffold No...

that is correct

tacit mortar Jul 13, 2021, 4:12 AM

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ionic jewel ,w (x-6)/(x+2) <= (x+2)/(x-6)

its correct right?

upper pebble Jul 13, 2021, 4:13 AM

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it doesn't look like Wolfram's answer is the same as yours

topaz scaffold Jul 13, 2021, 4:13 AM

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Mmm

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And I trust Wolfram Alpha

upper pebble Jul 13, 2021, 4:16 AM

#

x^2 - 12x + 36 <= x^2 + 4x + 4
-12x + 36 <= 4x + 4
-16x + 32 <= 0
-16x <= -32
x <= 2

#

so we know 2 is greater than or equal to x

tacit mortar Jul 13, 2021, 4:16 AM

#

yes

upper pebble Jul 13, 2021, 4:17 AM

#

and -2 would result in a denominator being 0, so we also know x is greater than -2

#

same thing with 6

tacit mortar Jul 13, 2021, 4:18 AM

#

yes

#

so the answer is either x>6

#

or

pearl marlin Jul 13, 2021, 4:19 AM

#

Solve taking rhs on lhs

upper pebble Jul 13, 2021, 4:19 AM

#

idk where those integer solutions come from though

#

oh nvm

#

because +-1 and 0 are between -2 and 2, and 2 is of course 2

topaz scaffold Jul 13, 2021, 4:20 AM

#

pearl marlin Solve taking rhs on lhs

What do those stand for?

tacit mortar Jul 13, 2021, 4:20 AM

#

upper pebble because +-1 and 0 are between -2 and 2, and 2 is of course 2

ye

pearl marlin Jul 13, 2021, 4:20 AM

#

topaz scaffold What do those stand for?

Right hand side on left hand side

topaz scaffold Jul 13, 2021, 4:20 AM

#

Ah

upper pebble Jul 13, 2021, 4:22 AM

#

so doesn't that also mean all integers greater than 6 are solutions

#

yes ok

topaz scaffold Jul 13, 2021, 4:23 AM

#

Should be

pearl marlin Jul 13, 2021, 4:24 AM

#

it will

tacit mortar Jul 13, 2021, 4:24 AM

#

upper pebble so doesn't that also mean all integers greater than 6 are solutions

🤔

pearl marlin Jul 13, 2021, 4:25 AM

#

$\frac{x-6}{x+2} -\frac{x+2}{x-6} \leq 0$\ $\frac{-16(x-2)}{(x+2)(x-6)} \leq 0$

ocean sealBOT Jul 13, 2021, 4:25 AM

#

learn4math

tacit mortar Jul 13, 2021, 4:27 AM

#

ok so do yall get -2< x < 2

pearl marlin Jul 13, 2021, 4:29 AM

#

see it should be negative or equal to zero , now only posability are $-2 < x\leq 2$ and $x>6$ , you can easly check

ocean sealBOT Jul 13, 2021, 4:29 AM

#

learn4math

tacit mortar Jul 13, 2021, 4:30 AM

#

so the answers are either $-2 < x\leq 2$ and $x>6$

ocean sealBOT Jul 13, 2021, 4:30 AM

#

idkwhatnametoput

pearl marlin Jul 13, 2021, 4:30 AM

#

yes like $(-2,2] \cup (6, \infty)$

ocean sealBOT Jul 13, 2021, 4:30 AM

#

learn4math

tacit mortar Jul 13, 2021, 4:31 AM

#

i get it

#

one sec

tacit mortar Jul 13, 2021, 4:32 AM

#

pearl marlin yes like $(-2,2] \cup (6, \infty)$

this would the answer

#

after solving it all

tacit mortar Jul 13, 2021, 4:34 AM

#

pearl marlin yes like $(-2,2] \cup (6, \infty)$

and the number line would look like this

opal wyvern Jul 13, 2021, 4:34 AM

#

opal wyvern Jul 13, 2021, 5:12 AM

#

bumpy

rigid smelt Jul 13, 2021, 5:16 AM

#

you are misunderstanding

#

the first derivative is the speed, but the sign of that derivative does not represent if the speed is slowing down or accelerating

#

the sign of the second derivative, or the derivative of the speed, shows that

topaz scaffold Jul 13, 2021, 5:19 AM

#

Looks like a physics 1 question

#

Usually people don't know calc then

rigid smelt Jul 13, 2021, 5:19 AM

#

pretty sure its not physics

#

because this is a very typical exercise of calc

topaz scaffold Jul 13, 2021, 5:19 AM

#

I took physics just last year

rigid smelt Jul 13, 2021, 5:20 AM

#

trust me but i take physics too

topaz scaffold Jul 13, 2021, 5:20 AM

#

rigid smelt because this is a very typical exercise of calc

Oh I haven't taken calc in school

rigid smelt Jul 13, 2021, 5:20 AM

#

physics questions are not this easy

topaz scaffold Jul 13, 2021, 5:20 AM

#

Hmm

#

At the start of the year I got many questions like that

topaz scaffold Jul 13, 2021, 5:23 AM

#

opal wyvern

Anyways it slows down at the right of the bumps and speeds up down on the left I believe

rigid smelt Jul 13, 2021, 5:23 AM

#

Please dont give out answers

topaz scaffold Jul 13, 2021, 5:23 AM

#

Oh why?

rigid smelt Jul 13, 2021, 5:24 AM

#

#❓how-to-get-help

#

People are here to learn and not to get spoon-fed

topaz scaffold Jul 13, 2021, 5:25 AM

#

Welp there's still another question

rigid smelt Jul 13, 2021, 5:25 AM

#

(Not directed to anyone, just generally speaking)

topaz scaffold Jul 13, 2021, 5:25 AM

#

Sorry 😅

#

To tell if the function is speeding up or slowing down you think about if the second derivative is positive or negative with positive being speeding up and negative being slowing down

#

You can find the sign by looking at the concavity of the function

vagrant kayak Jul 13, 2021, 5:40 AM

#

hellow

#

dark granite Jul 13, 2021, 5:42 AM

#

vagrant kayak

I can help with this

#

What have you tried so far?

vagrant kayak Jul 13, 2021, 5:42 AM

#

ok

dark granite Jul 13, 2021, 5:42 AM

#

@vagrant kayak

vagrant kayak Jul 13, 2021, 5:42 AM

#

i have tried till

#

i got the value as

#

2(n!)=1152

#

and then i dont get it

dark granite Jul 13, 2021, 5:42 AM

#

That's wrong

#

You should have $2(n!)^2=1152$

ocean sealBOT Jul 13, 2021, 5:43 AM

#

logician_pdx

vagrant kayak Jul 13, 2021, 5:43 AM

#

yeah

#

typo

dark granite Jul 13, 2021, 5:43 AM

#

kk

#

so divide both sides by 2

vagrant kayak Jul 13, 2021, 5:43 AM

#

ok

dark granite Jul 13, 2021, 5:43 AM

#

and then square root

#

both sides

vagrant kayak Jul 13, 2021, 5:43 AM

#

ok

dark granite Jul 13, 2021, 5:43 AM

#

let me know what you get for n!

vagrant kayak Jul 13, 2021, 5:43 AM

#

ok

#

oh i got it

#

n=4

dark granite Jul 13, 2021, 5:44 AM

#

yes!

vagrant kayak Jul 13, 2021, 5:44 AM

#

right?

#

yay

dark granite Jul 13, 2021, 5:44 AM

#

nice job

vagrant kayak Jul 13, 2021, 5:44 AM

#

😄

dark granite Jul 13, 2021, 5:45 AM

#

Any other questions?

vagrant kayak Jul 13, 2021, 5:45 AM

#

u good in chemistry?

dark granite Jul 13, 2021, 5:45 AM

#

nope

vagrant kayak Jul 13, 2021, 5:45 AM

#

oof

dark granite Jul 13, 2021, 5:45 AM

#

this is a math server lol

vagrant kayak Jul 13, 2021, 5:45 AM

#

ik

#

ok will u do one thing

#

i will send screenshots

#

of my homework

#

and the answers

#

will u check them?

dark granite Jul 13, 2021, 5:46 AM

#

okay it depends on what kinda questions they are

#

but I can take a look

vagrant kayak Jul 13, 2021, 5:46 AM

#

pnc

dark granite Jul 13, 2021, 5:46 AM

#

oh I'm good with that

vagrant kayak Jul 13, 2021, 5:46 AM

#

permutations and combinations

dark granite Jul 13, 2021, 5:46 AM

#

yes

vagrant kayak Jul 13, 2021, 5:46 AM

#

omg

#

ok

dark granite Jul 13, 2021, 5:47 AM

#

you gonna dm them to me? or post em here? either is fine

vagrant kayak Jul 13, 2021, 5:47 AM

#

dm would be better ig

dark granite Jul 13, 2021, 5:47 AM

#

kk sounds good

vagrant kayak Jul 13, 2021, 5:47 AM

#

ok

dark granite Jul 13, 2021, 5:48 AM

#

I'll open up this channel for other questions then

#

This channel is open for questions

opal wyvern Jul 13, 2021, 5:48 AM

#

Why did my wife leave me

zenith hemlock Jul 13, 2021, 6:00 AM

#

-ke^(-2k) = -3
e as exponential. find k. Help please.

fallow jasper Jul 13, 2021, 6:06 AM

#

Lambert W function

#

$-2ke^{-2k}=-6$

$-2k=W(-6)$

$k=\frac{-W(-6)}{2}$

ocean sealBOT Jul 13, 2021, 6:07 AM

#

Blackdeath39

tacit mortar Jul 13, 2021, 6:14 AM

#

Hi

#

for this question i got this as my answer $[-1 - \sqrt{3}, 0) \cup [\sqrt{3} - 1, \infty)$

ocean sealBOT Jul 13, 2021, 6:17 AM

#

idkwhatnametoput

tacit mortar Jul 13, 2021, 6:17 AM

#

right or wrong

cobalt ledge Jul 13, 2021, 6:26 AM

#

Wew

buoyant edge Jul 13, 2021, 6:27 AM

#

!!

dull olive Jul 13, 2021, 6:27 AM

#

I can't solve this for the life of me

tacit mortar Jul 13, 2021, 6:28 AM

#

tacit mortar Hi

<@&286206848099549185>

dull olive Jul 13, 2021, 6:28 AM

#

Oh sorry, I'll post my question somewhere else

tacit mortar Jul 13, 2021, 6:29 AM

#

its ok 👍

pearl marlin Jul 13, 2021, 6:29 AM

#

Make quadretic in 2^x

pearl marlin Jul 13, 2021, 6:29 AM

#

dull olive Oh sorry, I'll post my question somewhere else

Make quadretic in 2^x

dull olive Jul 13, 2021, 6:29 AM

#

How do I do that? #help-2

sturdy glen Jul 13, 2021, 6:35 AM

#

if I already know the eigenvalues of a matrix, how do i find the eigenbases?

pearl marlin Jul 13, 2021, 6:36 AM

#

sturdy glen if I already know the eigenvalues of a matrix, how do i find the eigenbases?

Use Ax = ex

(A-eI)x= 0 , solve this you will get eigenvector corospinding to eigenvalue e

sturdy glen Jul 13, 2021, 6:37 AM

#

is that just the same as the eigenbases?

tacit mortar Jul 13, 2021, 6:40 AM

#

ocean seal **idkwhatnametoput**

im pretty sure this is correct, may someone double check this

pearl marlin Jul 13, 2021, 6:41 AM

#

sturdy glen is that just the same as the eigenbases?

https://math.stackexchange.com/questions/1409350/what-is-an-eigenbasis-and-how-do-i-calculate-it-with-the-information-below

Mathematics Stack Exchange

What is an Eigenbasis and how do I calculate it with the informatio...

I have the matrix

$$A = \begin{bmatrix}
4 & 2 & 2\
2 & 4 & 2\
2 & 2 & 4
\end{bmatrix}$$

I've calculated the Eigenvalues and Eigenvectors as follows with help in a previous

upper pebble Jul 13, 2021, 6:41 AM

#

,w 1/x - x/2 <= 1

ocean sealBOT Jul 13, 2021, 6:41 AM

#

Results provided by WolframAlpha

Click here to refine your query online
Upgrade to WolframAlpha Pro!

pearl marlin Jul 13, 2021, 6:51 AM

#

tacit mortar for this question i got this as my answer $[-1 - \sqrt{3}, 0) \cup [\sqrt{3} - 1...

$\frac{2-x^2}{2x}-1 \leq 0$\

$\frac{2-x^2-2x}{2x}\leq 0$\ can you check now

ocean sealBOT Jul 13, 2021, 6:51 AM

#

learn4math

tacit mortar Jul 13, 2021, 6:54 AM

#

pearl marlin $\frac{2-x^2}{2x}-1 \leq 0$\\ $\frac{2-x^2-2x}{2x}\leq 0$\\ can you check now

alright i checked and got it correct ty

#

👍

alpine sable Jul 13, 2021, 7:24 AM

#

How can I get the average value of this graph (positive)?

rich basin Jul 13, 2021, 7:49 AM

#

Screen_Shot_2021-07-13_at_5.49.03_pm.png

#

i entered 40 into it because it is the highest value, however it is apparantly wrong

#

But i don't get why is that the case

rich basin Jul 13, 2021, 8:06 AM

#

<@&286206848099549185>

acoustic abyss Jul 13, 2021, 8:08 AM

#

help plz

#

rich basin Jul 13, 2021, 8:11 AM

#

sorry this channel si busy

dense rock Jul 13, 2021, 8:23 AM

#

Boruto look at the question from different perspective - they ask what is the maximum of f(x) - in order to do that you need to differentiate f(x) once, you'll get a quadratic equation to solve

alpine sable Jul 13, 2021, 8:25 AM

#

what do i have to multiply 2^x by to give 2^-x?

#

anyone?

#

2^(-2x)

#

yes

rich basin Jul 13, 2021, 8:26 AM

#

@dense rock Yeah that is what i did and when i instert 40 and the local maximun, it is not the global maximun

alpine sable Jul 13, 2021, 8:26 AM

#

oh ok

#

ty

dense rock Jul 13, 2021, 8:29 AM

#

rich basin <@!864415516520218655> Yeah that is what i did and when i instert 40 and the loc...

if you solved the quadratic equation you received two possible x's , simply by inserting them to the original function would give you the correct x

#

(40 is not one of those x's)

rich basin Jul 13, 2021, 8:30 AM

#

but then 40 is greater than one of the xs

#

when plugged into the function

#

when i plug 40 in, it gives out 3333.333

#

whereas when i plus in 15, the local maximun

#

it gives out 2213

low gorge Jul 13, 2021, 8:31 AM

#

acoustic abyss

$\frac56 (d+9)+7b$

ocean sealBOT Jul 13, 2021, 8:31 AM

#

Leopard

rich basin Jul 13, 2021, 8:33 AM

#

@dense rock but then 40 is greater than one of the x's when plugged into

dense rock Jul 13, 2021, 8:36 AM

#

rich basin <@!864415516520218655> but then 40 is greater than one of the x's when plugged i...

Ah i see, indeed with questions like that you need to check boundaries as well, 40 is the right answer

rich basin Jul 13, 2021, 8:39 AM

#

so the answer is wrong?

dense rock Jul 13, 2021, 8:39 AM

#

acoustic abyss

Please send the full question , it's not understood what needs to be done

dense rock Jul 13, 2021, 8:40 AM

#

rich basin so the answer is wrong?

What's written in your book?

rich basin Jul 13, 2021, 8:45 AM

#

@dense rock it is using 15 for the answer

dense rock Jul 13, 2021, 8:46 AM

#

then the book is wrong, they differentiated the equation, but forgot to check the boundaries👍

acoustic abyss Jul 13, 2021, 8:55 AM

#

low gorge $\frac56 (d+9)+7b$

tysm! i got the same answer, just checking :)

low gorge Jul 13, 2021, 8:55 AM

#

acoustic abyss tysm! i got the same answer, just checking :)

Okay

unborn sleet Jul 13, 2021, 9:41 AM

#

Hi guys, I have a question that may seem dumb, while I was reading a textbook I found this: "(v^2-9) has no common factors other than 1 and -1", I do understand the 1 but why also the -1?

somber osprey Jul 13, 2021, 9:46 AM

#

a

nova anvil Jul 13, 2021, 9:52 AM

#

is the normal riemann/darboux integral $\int_a^b f(x)dx$ by definition only meant to deal with bounded functions?

ocean sealBOT Jul 13, 2021, 9:52 AM

#

Anticipation

nova anvil Jul 13, 2021, 9:53 AM

#

ah nvm i think i know why it is true

grand sundial Jul 13, 2021, 9:57 AM

#

#

excuse me, may I ask why this is the case?

slim siren Jul 13, 2021, 10:06 AM

#

grand sundial

because if you sub 1 in to that equation there are no values because the number inside the brackets will equal 0, ultimately making 0 = 0 which means that there are no values for y

#

not sure if thats a good explanation but let me know if you want me to elaborate

grand sundial Jul 13, 2021, 10:12 AM

#

alright, thanks for the explanation, I understand it now, greatly appreciated

tender plinth Jul 13, 2021, 10:28 AM

#

#

not sure on how to do (i)

thorn tapir Jul 13, 2021, 10:29 AM

#

Similar triangles?

#

r/R = x/(x + d)

tender plinth Jul 13, 2021, 10:30 AM

#

Ahh

#

aight i got it thanks

#

that was so dumb of me

thorn tapir Jul 13, 2021, 10:30 AM

#

No problems, always glad to help

tender plinth Jul 13, 2021, 10:30 AM

#

thank you

thorn tapir Jul 13, 2021, 10:30 AM

#

tender plinth that was so dumb of me

Don't worry, it happens to everyone 👍

alpine sable Jul 13, 2021, 10:44 AM

#

is it possible to do this without a calculator?

dawn wraith Jul 13, 2021, 10:45 AM

#

Take log base 7 on both sides.

#

And from there I suppose it’s impossible.

#

But there must be some kind of way

#

Or an approximation

alpine sable Jul 13, 2021, 10:46 AM

#

oh ok thankls

dawn wraith Jul 13, 2021, 10:50 AM

#

Just found a way.

#

@alpine sable
I’ll give you a hint, try using the derivative.

rich basin Jul 13, 2021, 10:58 AM

#

Screen_Shot_2021-07-13_at_8.58.19_pm.png

#

i need help with (b)

dawn wraith Jul 13, 2021, 11:04 AM

#

Use the derivative.

#

Take it with respect to r.

thorn tapir Jul 13, 2021, 11:05 AM

#

rich basin i need help with (b)

dawn wraith Jul 13, 2021, 11:06 AM

#

Or just send him the answer, why don’t ya

thorn tapir Jul 13, 2021, 11:07 AM

#

For why it gives the maximum value, you need to do another derivative of dV/dr

#

to get d^2V/dr^2

#

put the calculated value of r there

#

if the expression is negative, the value is indeed maximum for that r

upper pebble Jul 13, 2021, 11:08 AM

#

nice fingers

thorn tapir Jul 13, 2021, 11:09 AM

#

I'm slowly turning into a ghost

dawn wraith Jul 13, 2021, 11:10 AM

#

He should do it by himself, not just get the answer as if it was free bud.

upper pebble Jul 13, 2021, 11:11 AM

#

stare

alpine sable Jul 13, 2021, 11:18 AM

#

#

what happened here

#

from first to last line

#

could someone please explain why I have to reject negative for x=plus or min square root 7

#

when finding x

rich basin Jul 13, 2021, 11:24 AM

#

You can't have negative answers in logs

#

Screen_Shot_2021-07-13_at_9.24.59_pm.png

#

How do you even find for xlnx

thorn tapir Jul 13, 2021, 11:25 AM

#

rich basin How do you even find for xlnx

calculator, or a log table

rich basin Jul 13, 2021, 11:26 AM

#

So there is no other way doing it algebraically

thorn tapir Jul 13, 2021, 11:26 AM

#

actually wait

#

you know n log x = log x^n

#

?

rich basin Jul 13, 2021, 11:26 AM

#

yes

thorn tapir Jul 13, 2021, 11:26 AM

#

Yeah try that

rich basin Jul 13, 2021, 11:26 AM

#

so you mean x^2 = e^1

thorn tapir Jul 13, 2021, 11:26 AM

#

no

#

x^x = e

rich basin Jul 13, 2021, 11:27 AM

#

yeah

#

that is hard as well

manic quail Jul 13, 2021, 11:27 AM

#

||Use Lambert W function||

thorn tapir Jul 13, 2021, 11:28 AM

#

Can i see what is the question

alpine sable Jul 13, 2021, 11:28 AM

#

😭

rich basin Jul 13, 2021, 11:28 AM

#

Screen_Shot_2021-07-13_at_9.28.26_pm.png

#

This an example question

alpine sable Jul 13, 2021, 11:28 AM

#

the room was MINE stareFlushed

thorn tapir Jul 13, 2021, 11:28 AM

#

.... actually true.

jagged raptor Jul 13, 2021, 11:28 AM

#

newtons method and a couple hours lol

rich basin Jul 13, 2021, 11:29 AM

#

manic quail ||Use Lambert W function||

How do we use that?

thorn tapir Jul 13, 2021, 11:29 AM

#

rich basin

bro.

#

you are given the value already

rich basin Jul 13, 2021, 11:29 AM

#

even if, but how can we use Lambert W function

#

to find the values

thorn tapir Jul 13, 2021, 11:29 AM

#

you don't need it

rich basin Jul 13, 2021, 11:29 AM

#

how do we use it though if we don't have the values

alpine sable Jul 13, 2021, 11:30 AM

#

you don't analytically

manic quail Jul 13, 2021, 11:30 AM

#

There's no button on your calculator, I presume, so you will need to use a computer.

alpine sable Jul 13, 2021, 11:30 AM

#

but numerically

thorn tapir Jul 13, 2021, 11:30 AM

#

You can use some identities but I doubt any numerical value can be done by hand 😂

#

The function is kind of crazy

#

leave it to the computers

rich basin Jul 13, 2021, 11:31 AM

#

so to use Lambert W function you need a computer?

manic quail Jul 13, 2021, 11:31 AM

#

You can't compute it otherwise.

rich basin Jul 13, 2021, 11:31 AM

#

okay

thorn tapir Jul 13, 2021, 11:31 AM

#

..uhm Yeah

manic quail Jul 13, 2021, 11:32 AM

#

But in your case, x=e^{W(1)}

rich basin Jul 13, 2021, 11:32 AM

#

Screen_Shot_2021-07-13_at_9.32.11_pm.png

#

then how do we do d

#

please

#

I got e^x(1-4) = 0

#

and then x = ln(0)k, but that would be an error

thorn tapir Jul 13, 2021, 11:33 AM

#

rich basin

just as I did in the volume question

#

derivative

manic quail Jul 13, 2021, 11:33 AM

#

Take the derivative, and set it equal to 0.

rich basin Jul 13, 2021, 11:34 AM

#

That is what i used

#

part (a) has the derivative i used

thorn tapir Jul 13, 2021, 11:34 AM

#

nice

rich basin Jul 13, 2021, 11:34 AM

#

but then i did not get the answer

thorn tapir Jul 13, 2021, 11:34 AM

#

you're getting there

rich basin Jul 13, 2021, 11:34 AM

#

e^t(1-4)

#

and make it 0 to find the stationary point

#

which would mean e^t = 0

#

but then e has no way of becoming a zero

woven crane Jul 13, 2021, 11:34 AM

#

rich basin e^t(1-4)

no, check again the second term in your derivative

#

they aren't both e^t

thorn tapir Jul 13, 2021, 11:35 AM

#

yeah

plucky sleet Jul 13, 2021, 11:35 AM

#

rich basin e^t(1-4)

it's
e^(t)(1-4e^(-2t))=0

thorn tapir Jul 13, 2021, 11:35 AM

#

if you did the derivative

#

set it to zero

#

it'll automatically give

#

e^(2t) = 4

#

and then you have e^t

#

put it back on y

rich basin Jul 13, 2021, 11:36 AM

#

nice i managed to get the answer

#

thanks

thorn tapir Jul 13, 2021, 11:36 AM

#

welcome 👍

rich basin Jul 13, 2021, 11:36 AM

#

made a very noob mistake

alpine sable Jul 13, 2021, 11:37 AM

#

#

Can anyone help me solving this problem?

glass lichen Jul 13, 2021, 11:38 AM

#

looks seperable

thorn tapir Jul 13, 2021, 11:40 AM

#

multiply the whole thing by sec^2 x

#

you'll get it

alpine sable Jul 13, 2021, 11:42 AM

#

#

#

i tried solving it but i think i am wrong somewhere!

glass lichen Jul 13, 2021, 11:43 AM

#

yeah, it's a seperable DE

#

$\cos^2(x)\dv{y}{x}=1-y$

ocean sealBOT Jul 13, 2021, 11:43 AM

#

Mosh

thorn tapir Jul 13, 2021, 11:44 AM

#

Just take y and x in different sides

glass lichen Jul 13, 2021, 11:45 AM

#

yeah... like I said

thorn tapir Jul 13, 2021, 11:45 AM

#

you don't even need any integrating factors

echo python Jul 13, 2021, 11:46 AM

#

how can I calculate the angle like this based on 2 coordinate sets?

#

maybe something with arctan?

glass lichen Jul 13, 2021, 11:48 AM

#

echo python maybe something with arctan?

yes

#

since you can easily get the legs of the corresponding right triangle

sour basin Jul 13, 2021, 12:08 PM

#

#

How do I get this help!

glass lichen Jul 13, 2021, 12:09 PM

#

sour basin

what are you stuck on?

sour basin Jul 13, 2021, 12:09 PM

#

Im not sure how to get the 1-(-1)^n/n

glass lichen Jul 13, 2021, 12:11 PM

#

$\int \sin(nx)\dd{x}=\frac{1}{n}\int n\sin(nx)\dd{x} =-\frac{1}{n}\cos(nx)$

ocean sealBOT Jul 13, 2021, 12:11 PM

#

Mosh

sour basin Jul 13, 2021, 12:11 PM

#

where did the (-1)^n come from?

glass lichen Jul 13, 2021, 12:11 PM

#

plugging in x=pi

#

since cos(integer multiple of pi) will either be 1 or -1

sour basin Jul 13, 2021, 12:11 PM

#

Oh is it because this has multiple solutions

glass lichen Jul 13, 2021, 12:12 PM

#

$\cos(n\pi)=1$ if n is even and $\cos(n\pi)=-1$ if n is odd

ocean sealBOT Jul 13, 2021, 12:12 PM

#

Mosh

sour basin Jul 13, 2021, 12:13 PM

#

Oh

#

Ohh Ok

#

So n accounts for that change

#

(-1)^n

glass lichen Jul 13, 2021, 12:13 PM

#

yes

#

$n\in\mathbb{Z}\implies \cos(n\pi)=(-1)^n$

ocean sealBOT Jul 13, 2021, 12:14 PM

#

Mosh

sour basin Jul 13, 2021, 12:16 PM

#

also just a question

#

im kinda confused on whats the point of a fourier series

vale sapphire Jul 13, 2021, 12:16 PM

#

okay

#

so, especially in physics, a lot of times you submit some system to a given signal, and see how it responds

#

for many systems (electrical, anything that has to do with waves, so really a lot of things), the response is basically linear

#

meaning that the response to a sum of signals is just the sum of the responses to each signal individually

#

As it turns out, sinusoids are rather handy signal shapes

#

they model oscillations which you find all over the place in physics

sour basin Jul 13, 2021, 12:18 PM

#

Oh

vale sapphire Jul 13, 2021, 12:19 PM

#

And they're simple enough that you have good tools to calculate the responses to sinusoids in a lot of cases

#

For example with electrical systems

sour basin Jul 13, 2021, 12:19 PM

#

But it seems that most of the function that I calculate arent really sinosoidal in nature like Lines, then discontinuity

vale sapphire Jul 13, 2021, 12:19 PM

#

But of course, not everything is a sinusoid

#

the step function is a common example of this

#

What Fourier showed is that any signal can be decomposed into a sum of sinusoids of different amplitudes and frequencies

sour basin Jul 13, 2021, 12:20 PM

#

Oh

#

And it is given as a function

vale sapphire Jul 13, 2021, 12:21 PM

#

Since it's a sum, you can use the linearity of your system, and only consider sinusoidal responses

#

And you're then easily able to calculate the response to the actual signal

sour basin Jul 13, 2021, 12:22 PM

#

So if we have a contuinity would the funciton converge to a point?

vale sapphire Jul 13, 2021, 12:22 PM

#

a discontinuity?

sour basin Jul 13, 2021, 12:22 PM

#

Yea

#

How can something converge to a value if its repeated over time

vale sapphire Jul 13, 2021, 12:23 PM

#

(There are some technicalities : for example, periodic signals have a nice Fourier expansion ; a discrete sum of sinusoids with all frequencies being integer multiples of a base frequency. For non-periodic signals, that becomes an integral)

#

Hang on, there should be some nice animation somewhere out there

#

https://miro.medium.com/max/1584/1*WUhA-jOE2ta5Rar6XNuDxg.gif

woven crane Jul 13, 2021, 12:25 PM

#

https://www.jezzamon.com/fourier/ has interactive^ you can draw a wave and it decomposes into the fourier modes

vale sapphire Jul 13, 2021, 12:25 PM

#

here, you see a rectangular wave being progressively approximated with sums of sinusoids

vague coral Jul 13, 2021, 12:26 PM

#

I've seen someone doing animation on Desmos while using Fourier

sour basin Jul 13, 2021, 12:27 PM

#

Oh Ok

#

Then for all x in the interval (p, p) the Fourier series of f converges to f (x) at a point
of continuity

#

What does this mean

vale sapphire Jul 13, 2021, 12:29 PM

#

It means that if a function is continuous as a given point, the sum of sinusoids will get arbitrarily close to the function's value at that point

sour basin Jul 13, 2021, 12:29 PM

#

Oh

#

so like an accurate estimate

vale sapphire Jul 13, 2021, 12:30 PM

#

yeah, "arbitrarily close" is what a limit is

sour basin Jul 13, 2021, 12:30 PM

#

Mk

#

Ohhh Okay i get it

#

So like at every x value the function will converge to f(x) but if x is a discontinuty it will converge to f(+x) + f(x-)/2

vale sapphire Jul 13, 2021, 12:33 PM

#

if x is a discontinuity who knows

acoustic sableBOT Jul 13, 2021, 12:33 PM

#

vale sapphire Jul 13, 2021, 12:33 PM

#

wrong command

echo python Jul 13, 2021, 12:33 PM

#

echo python how can I calculate the angle like this based on 2 coordinate sets?

would this formula be correct? atan2(y2-y1, x2-x1) * (180 / pi)?

vale sapphire Jul 13, 2021, 12:33 PM

#

it might converge to some arbitrary value, or it might not

sour basin Jul 13, 2021, 12:34 PM

#

Kk

vale sapphire Jul 13, 2021, 12:34 PM

#

echo python would this formula be correct? `atan2(y2-y1, x2-x1) * (180 / pi)`?

that seems correct

acoustic abyss Jul 13, 2021, 12:35 PM

#

anyone b bit plz?

acoustic abyss Jul 13, 2021, 12:35 PM

#

acoustic abyss anyone b bit plz?

is the answer - 3y = 10g * 4w

alpine sable Jul 13, 2021, 12:36 PM

#

its not -3y

#

u move the 3 to the rhs

#

leaving only the y

sour basin Jul 13, 2021, 12:36 PM

#

is this integration right?

vale sapphire Jul 13, 2021, 12:37 PM

#

yes?

glass lichen Jul 13, 2021, 12:37 PM

#

looks right

sour basin Jul 13, 2021, 12:37 PM

#

Nvm it is

glass lichen Jul 13, 2021, 12:37 PM

#

$\frac{2}{L}\left[\frac{x^3}{3}\right]_0^L$

ocean sealBOT Jul 13, 2021, 12:37 PM

#

Mosh

south mesa Jul 13, 2021, 12:43 PM

#

Can someone explain this please

#

#

I don’t understand how to do it

acoustic abyss Jul 13, 2021, 12:43 PM

#

alpine sable its not -3y

sheesh when did u join

#

3rd bit?

#

<@&286206848099549185>

tepid crystal Jul 13, 2021, 12:45 PM

#

Can someone explain how this happened ?

glass lichen Jul 13, 2021, 12:47 PM

#

tepid crystal Can someone explain how this happened ?

log properties

#

$e^{\ln(x)}=x$

ocean sealBOT Jul 13, 2021, 12:47 PM

#

Mosh

glass lichen Jul 13, 2021, 12:48 PM

#

$n\log_a(x)=\log_a(x^n)$

ocean sealBOT Jul 13, 2021, 12:48 PM

#

Mosh

tepid crystal Jul 13, 2021, 12:48 PM

#

glass lichen log properties

I didnt know about this one. Thanks

glass lichen Jul 13, 2021, 12:49 PM

#

I mean that's how logs are defined catshrug

tepid crystal Jul 13, 2021, 12:49 PM

#

I am not taught logs properly yet.

#

was just doing some extra questions

vale ridge Jul 13, 2021, 12:58 PM

#

the endpoints of a diameter of a cirlce are A(6,-8) and B(-7,-4> What are the coordinates of the centre of the circle.

quartz lark Jul 13, 2021, 12:59 PM

#

Yo

#

r(t)=(t,9-t,2t)

#

What is the curve of this vector

glass lichen Jul 13, 2021, 1:12 PM

#

you mean curvature?

south mesa Jul 13, 2021, 1:12 PM

#

vale ridge the endpoints of a diameter of a cirlce are A(6,-8) and B(-7,-4> What are the co...

Use distance formula to find the diameter. Divide it by 2 to get the radius and plug it into the equation of a circle. Then make an equation for both points (ex: (6-h)^2 + (-8-k)^2 = r^2 ). Since they are both equal to r^2, set them equal to each other and simplify. Make one of the variables equal to an expression containing the other so that you can use substitution. Then use substitution to find the value of one variable, and then use that value to find the value of the other variable. Once you know h and k you know the center point.

glass lichen Jul 13, 2021, 1:13 PM

#

$\kappa (t)=\frac{\abs{T'(t)}}{\abs{r'(t)}}$?

ocean sealBOT Jul 13, 2021, 1:13 PM

#

Mosh

vagrant rover Jul 13, 2021, 1:16 PM

#

Is this 17.1 deg?

upper pebble Jul 13, 2021, 1:32 PM

#

acoustic abyss 3rd bit?

do you still need help with this?

#

also you're not supposed to ping the Helpers role unless your question has been unanswered for 15 minutes according to #❓how-to-get-help

unreal depot Jul 13, 2021, 1:37 PM

#

can some1 help me out

alpine sable Jul 13, 2021, 1:39 PM

#

You know there are 3 red, 7 black and 5 green, which is a total of 15 marbles.

vale wigeon Jul 13, 2021, 1:39 PM

#

or to make that less superfluous, 7 black and 8 not black for a total of 15

alpine sable Jul 13, 2021, 1:39 PM

#

The probability that the first marbles selected is black is 7/15

#

If there is no replacement, that means that the second time you pick a marble, there will only be 6 that are black.

acoustic abyss Jul 13, 2021, 1:41 PM

#

upper pebble also you're not supposed to ping the Helpers role unless your question has been ...

oh ok ty

alpine sable Jul 13, 2021, 1:41 PM

#

And a total of 14 marbles

shrewd otter Jul 13, 2021, 1:41 PM

#

vagrant rover ```At what angle should the roadway on a curve with a 50 m radius be banked to a...

If the roadway is frictionless, this question makes no sense.

alpine sable Jul 13, 2021, 1:41 PM

#

Which means that the probability of picking a black marble the second time is 6/14

#

You should do this two more times and multiply all the probabilities you've got

echo python Jul 13, 2021, 1:49 PM

#

I have 2 vectors, [x, y, z] and [x, y, z]. How can I calculate the 180 degree angle between both y coordinates?

shrewd otter Jul 13, 2021, 1:49 PM

#

echo python I have 2 vectors, [x, y, z] and [x, y, z]. How can I calculate the 180 degree an...

Pardon?

echo python Jul 13, 2021, 1:50 PM

#

?

alpine sable Jul 13, 2021, 1:50 PM

#

echo python I have 2 vectors, [x, y, z] and [x, y, z]. How can I calculate the 180 degree an...

you mean the angle between the vectors?

echo python Jul 13, 2021, 1:50 PM

#

only the y values, I can already calculate the angle between x and z with an arctan formula

shrewd otter Jul 13, 2021, 1:51 PM

#

The angle between two y values is... 0.

#

Since they're colinear.

echo python Jul 13, 2021, 1:51 PM

#

huh

shrewd otter Jul 13, 2021, 1:52 PM

#

Well, 0 or 180.

echo python Jul 13, 2021, 1:52 PM

#

actually I meant, z, my bad. so basically the height degree

#

say one vector is like [0, 0, 30] and the other [0, 0, 45] then the angle would be 45 degrees or so

#

talking about coordinates here^^

thorn tapir Jul 13, 2021, 1:53 PM

#

they lie in same line

#

the example you provided

echo python Jul 13, 2021, 1:53 PM

#

wait thats right

#

okay wait let me grab real world vectors, one sec

jagged trout Jul 13, 2021, 1:54 PM

#

echo python actually I meant, z, my bad. so basically the height degree

Do you want a vector which is 90° on the other vectors?

alpine sable Jul 13, 2021, 1:55 PM

#

Lau, what are you trying to do aimbot or something?

echo python Jul 13, 2021, 1:55 PM

#

well yeah and no. I'm trying to make a video game character that shoots the player

alpine sable Jul 13, 2021, 1:56 PM

#

If you have a direction two direction vectors, turn them into euler angles

#

easier to work like that

echo python Jul 13, 2021, 1:56 PM

#

83.9572 170.509 11.5``` the vectors for reference; first one is the AI the other one is the player

jagged trout Jul 13, 2021, 1:56 PM

#

Did you use Unity?

echo python Jul 13, 2021, 1:56 PM

#

no, I'm challenging myself to code it entirely myself

alpine sable Jul 13, 2021, 1:56 PM

#

Those are already angles

#

Or is it origin

echo python Jul 13, 2021, 1:56 PM

#

its x, y, z

#

x for length y for depth z for height

alpine sable Jul 13, 2021, 1:57 PM

#

So you take the two vectors subtract them from eachother and normalize them

#

Then you negate it, and it will be 180

unreal depot Jul 13, 2021, 1:59 PM

#

any1 down to help?

shrewd otter Jul 13, 2021, 1:59 PM

#

unreal depot any1 down to help?

Let's look at a simpler case.

echo python Jul 13, 2021, 2:00 PM

#

alpine sable Then you negate it, and it will be 180

wym with negating it?

shrewd otter Jul 13, 2021, 2:00 PM

#

Actually, this chat is occupied, you dunderhead.

alpine sable Jul 13, 2021, 2:00 PM

#

Negating a number is just like

#

if you have 2 and you negate it. its -2

unreal depot Jul 13, 2021, 2:01 PM

#

shrewd otter Actually, this chat is occupied, you dunderhead.

what do you mean?

shrewd otter Jul 13, 2021, 2:01 PM

#

Someone is already using this chat to have a question solved.

echo python Jul 13, 2021, 2:01 PM

#

so basically inverting the number so -2 becomes 2 and 1 becomes -1 or like reverse absolute?

alpine sable Jul 13, 2021, 2:01 PM

#

I'm only saying it you should negate it, because you mentioned you wanted to turn it 180

shrewd otter Jul 13, 2021, 2:01 PM

#

You can't bump in and bury their problem.

echo python Jul 13, 2021, 2:01 PM

#

no

#

I want to calculate the value of the rotation needed

alpine sable Jul 13, 2021, 2:01 PM

#

So if you have a direction vector, and you negate it - it will point in the opposite direction

echo python Jul 13, 2021, 2:01 PM

#

for the AI to point at the player

#

based on the coords of the player and those of the ai

#

but only the y value considering I already have the rest

alpine sable Jul 13, 2021, 2:02 PM

#

Right so

#

You have two player coordinates - p1 and p2

#

if you want p2 to point at p1, you do:

(p2 - p1)

#

Then you have a direction vector that points from p2 to p1

echo python Jul 13, 2021, 2:03 PM

#

huh, wouldn't that just be the difference between the coords

alpine sable Jul 13, 2021, 2:04 PM

#

Yes, but that's also a direction

echo python Jul 13, 2021, 2:05 PM

#

then just multiply the difference of the y value by pi / 180?

#

wait

alpine sable Jul 13, 2021, 2:06 PM

#

well, that thing

#

is turning the direction vector into euler angles

echo python Jul 13, 2021, 2:07 PM

#

wait is that what a euler angle is

#

that might actually be what I need

alpine sable Jul 13, 2021, 2:07 PM

#

atan2( diffVec.y, diffVec.x ) * 180.f / 3.14

#

= y

echo python Jul 13, 2021, 2:08 PM

#

why x instead of z?

alpine sable Jul 13, 2021, 2:08 PM

#

what do you mean instead of z

echo python Jul 13, 2021, 2:08 PM

#

the vector has x, y and z

#

its 3d

alpine sable Jul 13, 2021, 2:08 PM

#

yea, i understand, but you dont need Z in the angle

echo python Jul 13, 2021, 2:09 PM

#

but then wouldn't it only work if the ai is next to the player on the x axis?

alpine sable Jul 13, 2021, 2:10 PM

#

ok, so

#

after calculating p2-p1, u have a direction vector. lets say it could be x 100, y 50, z 20

#

But what u want is an euler angle, so u gotta translate it.

#

U didnt need to do this if the game accepted a direction vector, so it doesn't.

#

This angle kinda looks like a vector, but its not 'x y z', its 'pitch, yaw, roll'

#

the Z component in the angle is the roll, you dont need this

#

like if you change roll, you will 'tilt' your view

#

if you change roll enough, it will make ur player be 'upside down'

#

you cannot be upside down in assault cube, so thats why i say you dont need z

#

roll is good in airplane games, because you can turn your plane upside down, but not in assault cube

echo python Jul 13, 2021, 2:13 PM

#

ahhh like that

alpine sable Jul 13, 2021, 2:14 PM

#

so

#

u know how to calculate p2 - p1, and apparently you figured out how to find pitch

#

and i showed u the formula for yaw

#

and roll, you set that to 0

echo python Jul 13, 2021, 2:15 PM

#

alrightt

#

thanks a lot

alpine sable Jul 13, 2021, 2:17 PM

#

np

#

@echo python
p2 = 108.778 200.503 5.5
p1 = 83.9572 170.509 11.5

diff = p2 - p1

Normalize(diff);

angle.pitch = atan2( -diff.z, diff.Length2D( ) ) * 180 / 3.14
angle.yaw = atan2( diff.y, diff.x ) * 180 / 3.14;

#

so this

echo python Jul 13, 2021, 2:20 PM

#

allrightt

#

I had

float nLrRot = std::atan2(target.coords[1] - coords[1], target.coords[0] - coords[0]) * (180 / PI) + 90;
float nUdRot = std::atan2(target.coords[2] - coords[2], target.coords[1] - coords[1]) * (180 / PI);

#

again, thanks a lot

shrewd otter Jul 13, 2021, 2:22 PM

#

You should really be using tuples or dedicated types.

ivory granite Jul 13, 2021, 2:25 PM

#

#

can someone help me with this

thorn tapir Jul 13, 2021, 2:26 PM

#

Just simply find f'(x)

#

and check where f'(x) is > 0 and where < 0

#

if less than zero, then decreasing

#

and if greater, increasing

#

the question seems to have multiple options correct

ivory granite Jul 13, 2021, 2:29 PM

#

OOHHH

#

tysmm

shrewd otter Jul 13, 2021, 2:29 PM

#

thorn tapir the question seems to have multiple options correct

It does not?

glass lichen Jul 13, 2021, 2:30 PM

#

yeah it doesnt

thorn tapir Jul 13, 2021, 2:30 PM

#

maybe, I haven't did the calculations myself so I can't.be sure

shrewd otter Jul 13, 2021, 2:30 PM

#

Doesn't matter, the given options are all mutually contradictory.

thorn tapir Jul 13, 2021, 2:31 PM

#

Oh right, they have interchanged the state of the graph in C an D

#

oh, my mistake

rich haven Jul 13, 2021, 2:34 PM

#

is this a?

shrewd otter Jul 13, 2021, 2:54 PM

#

No, because those two triangles have the same 3 angles.

rich haven Jul 13, 2021, 2:57 PM

#

shrewd otter No, because those two triangles have the same 3 angles.

how are they congruent though

shrewd otter Jul 13, 2021, 2:58 PM

#

Ah, right, they don't have to be.

rich haven Jul 13, 2021, 2:58 PM

#

so its a?

shrewd otter Jul 13, 2021, 2:59 PM

#

Seems like it.

#

There may be more than one correct answer, though.

echo python Jul 13, 2021, 3:03 PM

#

alpine sable <@!764591424502235157> p2 = 108.778 200.503 5.5 p1 = 83.9572 170.509 11.5 diff...

turns out I was looking for float nUdRot = std::atan2(target.coords[2] - coords[2], abs(target.coords[0] - coords[0]) + abs(target.coords[1] - coords[1])) * 180 / PI;

#

thanks for putting me on the right track, tho

alpine sable Jul 13, 2021, 3:03 PM

#

oh ok

alpine sable Jul 13, 2021, 3:26 PM

#

@echo python actually, thats exactly the same as i sent u, just written differently xd

echo python Jul 13, 2021, 3:28 PM

#

oh

serene flame Jul 13, 2021, 3:42 PM

#

so i'm taking a look at the parametrization method to solve surface integrals. just learned those. and i can't understand why r(u,v) should be <2cos u, 2sin u, v> given S is x^2+y^2 = 4.
Above is the full problem

dry thunder Jul 13, 2021, 3:45 PM

#

any help?

serene flame Jul 13, 2021, 3:49 PM

#

sure

#

i'm supposing you're trying to find y

dry thunder Jul 13, 2021, 3:50 PM

#

ye

ionic jewel Jul 13, 2021, 3:50 PM

#

serene flame so i'm taking a look at the parametrization method to solve surface integrals. j...

try graphing the parametric form to see why it's the same circle

#

the v is a different variable for height, 0<=v =<8

#

i don't know a mathmatical way to show it off the top of my head but it's just the circle parametrization

#

unit circle of radius 2

#

x = 2cos(theta), y = 2sin(theta)

serene flame Jul 13, 2021, 3:53 PM

#

first off normalize 2y so that it coincides with the other denominators. you can easily do this, just multiply 2 by 3 and divide by 3, and you get 6y/3. Then multiply (4y-1) by 2/3
you get (8y-2)/3. Then distribute the minus sign to the new (6y/3 - (y+1)/3) and you overall get

(8y-2)/3 - 6y/3 + (y+1)/3 -y/3 = 4/3

ebon prism Jul 13, 2021, 3:54 PM

#

#

serene flame Jul 13, 2021, 3:54 PM

#

now you can straight up cancel the denominators by multiplying both sides by 3 and all that's left to do is sum the y terms and the known terms and get 3y-1 = 4. y is 5/3

ebon prism Jul 13, 2021, 3:55 PM

#

am i supposed to put arrows on the close circles too

#

?

serene flame Jul 13, 2021, 3:56 PM

#

ionic jewel try graphing the parametric form to see why it's the same circle

Thank you! you're a life saver, i didn't know the ruv equation was the way to plot the surface S

serene flame Jul 13, 2021, 3:57 PM

#

ebon prism am i supposed to put arrows on the close circles too

arrows on the closed circles? i don't think so

dry thunder Jul 13, 2021, 3:58 PM

#

thanks @serene flame

#

appreciate it!!!

serene flame Jul 13, 2021, 3:59 PM

#

yw

ebon prism Jul 13, 2021, 3:59 PM

#

serene flame arrows on the closed circles? i don't think so

yeah that's what im thinking. thanks

serene flame Jul 13, 2021, 4:04 PM

#

ionic jewel try graphing the parametric form to see why it's the same circle

sorry to bother again, but if i had S = x+y+z = 1, 1st octant, r(u, v) should be <1, -y, v> ?

ionic jewel Jul 13, 2021, 4:07 PM

#

serene flame sorry to bother again, but if i had S = x+y+z = 1, 1st octant, r(u, v) should be...

note that we can rewrite this to
z = 1-x-y, so
r(x,y) = <x,y, 1-x-y>

#

replace x and y as u and v if you care

#

with the restriction that x and y are both larger than 0 and x+y < 1

serene flame Jul 13, 2021, 4:10 PM

#

oh so it's not obligatory, also, so, z is reformulated. So if i got S = 1+x r(x, y) should be
<x, y, 1+x>

#

having a bit of a hard time with getting r

vagrant rover Jul 13, 2021, 4:16 PM

#


(A) force x distance 
(B) work x time 
(C) force x acceleration 
(D) force x velocity ```

#

Is this D?

void yoke Jul 13, 2021, 4:18 PM

#

P = E/t

#

E = 0.5mv^2 or mgh or fd

#

Yes d looks good.

vagrant rover Jul 13, 2021, 4:20 PM

#

#

Awesome aweosme

#

thanks!

gray oxide Jul 13, 2021, 4:36 PM

#

Hello

#

Question:

#

A cylindrical tank contains 20 000L water

#

Through a hole in the tank water runs out

#

Volume V after time t given by the formula

$$V(t) =20 000 - 800t + 8t^2 $$

ocean sealBOT Jul 13, 2021, 4:38 PM

#

!callidus

gray oxide Jul 13, 2021, 4:39 PM

#

The tank is empty after 50min

#

That is question A)

#

But question B) is

#

In the interval 0<t<a the speed of the water running through the hole is 600L/min decide a

#

How do I start with this?

glass lichen Jul 13, 2021, 4:40 PM

#

can you post the question as written?

gray oxide Jul 13, 2021, 4:40 PM

#

Sure

#

*in the interval of 0<t<a the speed of the water running out is 600Liters/min. Decide a

the formula is
V(t) =20000-800t+8t^2

and water runs out after 50min*

gray oxide Jul 13, 2021, 4:42 PM

#

glass lichen can you post the question *as written*?

Is that fine?

glass lichen Jul 13, 2021, 4:43 PM

#

I meant a picture of the question

gray oxide Jul 13, 2021, 4:43 PM

#

Do you read Swedish?

#

alpine sable Jul 13, 2021, 4:47 PM

#

A steel ball bearing is dropped from the roof of a building (the initial velocity of the ball is zero). An observer standing in front of a window 120 cm high notes that the ball takes 0.125 s to fall from the top to the bottom of the window. The ball bearing continues to fall, makes a completely elastic col- lision with a horizontal sidewalk, and reappears at the bottom of the window 2.0 s after passing it on the way down. How tall is the building? (The ball will have the same speed at a point going up as it had going down after a completely elastic collision.)

#

What does the second part of the problem mean? Does it mean that it takes 2 seconds for the ball to appear in the window at the top, and then again at the bottom when it comes back up

#

Or does it mean that it will be done passing it, and then come back up after 2 seconds

gray oxide Jul 13, 2021, 4:49 PM

#

alpine sable Or does it mean that it will be done passing it, and then come back up after 2 s...

It's occupied pls

alpine sable Jul 13, 2021, 4:49 PM

#

I posted it in #help-1 then

gray oxide Jul 13, 2021, 4:49 PM

#

alpine sable I posted it in <#269573202018041856> then

Thank you :)

#

Hope you understand the explanation easily

alpine sable Jul 13, 2021, 4:55 PM

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gray oxide Hope you understand the explanation easily

I don't think your question is clear

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What does part a) and b) ask?

gray oxide Jul 13, 2021, 4:55 PM

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I'll try to be clearer srr

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Part A was

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"how long time will it take before the tank is empty"

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I got that question right and it was 50min

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And I thought that maybe this info will be used in the B answer becuase my textbook does that a lot

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The B part was

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"in the interval of 0<t<a the outstream(outflow?) speed is 600liter per min, decide a"

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Does this make sense or what part is not making sense so I can try and be more clear?

alpine sable Jul 13, 2021, 5:01 PM

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Yeah so V'(t) = -800 + 16t, and so you want -800 + 16t = 600, which gives you 1400 = 16t and therefore t = 87.5

gray oxide Jul 13, 2021, 5:02 PM

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No I did that and that was wrong sadly :(

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Do you wanna know the correct time or do you like to keep it mysterious?

glass lichen Jul 13, 2021, 5:03 PM

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did you perhaps forget the word average speed...?

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and that 600L/min is an average?

alpine sable Jul 13, 2021, 5:04 PM

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Wait something is wrong

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It can't be an interval even

glass lichen Jul 13, 2021, 5:04 PM

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because as written you cant solve it

gray oxide Jul 13, 2021, 5:04 PM

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In the question it says that between 0 and a seconds/min /hours cuz i don't know what a is the speed is 600L/min

glass lichen Jul 13, 2021, 5:04 PM

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didnt answer my question

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at all

gray oxide Jul 13, 2021, 5:04 PM

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That means no

glass lichen Jul 13, 2021, 5:04 PM

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I asked if 600L/min is an average speed

gray oxide Jul 13, 2021, 5:04 PM

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There was no average word or similar word

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It just said

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600l/min

glass lichen Jul 13, 2021, 5:05 PM

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Ok then talk to your teacher, cause as written you cannot answer it.

alpine sable Jul 13, 2021, 5:05 PM

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@gray oxide What is the answer?

gray oxide Jul 13, 2021, 5:06 PM

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That's the answer

alpine sable Jul 13, 2021, 5:07 PM

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That's the average rate lol

gray oxide Jul 13, 2021, 5:07 PM

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I guess I should have assumed so then lol

alpine sable Jul 13, 2021, 5:07 PM

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V(a) is the volume at a minutes, and V(0) is the initial volume, divided by the elapsed time a, you get the average speed.

gray oxide Jul 13, 2021, 5:08 PM

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Ohhhhh

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Lol

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Gimme one sec I wanna solve dis

glass lichen Jul 13, 2021, 5:08 PM

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oh wow, average huh

gray oxide Jul 13, 2021, 5:11 PM

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glass lichen oh wow, **average** huh

Dude I told you.... It didn't say average or normal or anything like that it just said speed= 600

gray oxide Jul 13, 2021, 5:11 PM

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alpine sable V(a) is the volume at a minutes, and V(0) is the initial volume, divided by the ...

Either way thank you for the help and you 2 @glass lichen

alpine sable Jul 13, 2021, 5:12 PM

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I guess it can't be the derivative because the derivative is at a specific time, not an interval

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So you were supposed to assume it is the average speed, however I don't like that

glass lichen Jul 13, 2021, 5:12 PM

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derivative is instantaneous rate of change

alpine sable Jul 13, 2021, 5:12 PM

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Yeah

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So you would be finding the rate of change at a specific time, not an interval in your case

robust phoenix Jul 13, 2021, 5:28 PM

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hey guys i need some help

cinder wedge Jul 13, 2021, 5:29 PM

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robust phoenix hey guys i need some help

yes?

winged mica Jul 13, 2021, 5:30 PM

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can someone check what i sent in #help-2

robust phoenix Jul 13, 2021, 5:32 PM

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cinder wedge yes?

sinθ<0, m>0, tanθ=2m || find sin θ + cos θ
what should i do here
ik it needs to be a negative number both sinθ and cosθ

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and i know tan = sin/cos

shrewd otter Jul 13, 2021, 5:35 PM

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robust phoenix and i know tan = sin/cos

You know that this is > 0.

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So since sin < 0, cos must also be < 0.

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So you know you're in the 3rd quadrant.

robust phoenix Jul 13, 2021, 5:36 PM

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yeah i just said it both needs to negative(below zero)

shrewd otter Jul 13, 2021, 5:38 PM

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robust phoenix yeah i just said it both needs to negative(below zero)

Since you know you're in the 3rd quadrant, you know tangent is bijective.

robust phoenix Jul 13, 2021, 5:38 PM

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huh

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idk what a bijective is

shrewd otter Jul 13, 2021, 5:38 PM

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It means you can find θ.

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It's arctan(2m).

robust phoenix Jul 13, 2021, 5:39 PM

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Hurubon

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I have no idea what you just said

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If you have a video/book that i can read that from

shrewd otter Jul 13, 2021, 5:39 PM

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Every bijective function has an inverse function.

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So if g is the inverse of f, then if f(x) = y, then g(y) = x.

robust phoenix Jul 13, 2021, 5:40 PM

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shrewd otter So if g is the inverse of f, then if f(x) = y, then g(y) = x.

yeah i get it

shrewd otter Jul 13, 2021, 5:41 PM

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arctan is the inverse of tan.

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But I don't know how you can use this.

robust phoenix Jul 13, 2021, 5:41 PM

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well

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here's the answer

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it's 'b' but i have no idea how they got it