#help-0

1 messages · Page 738 of 1

dusk wedge
#

Hey, just a quick question, is it possible to compute the eigenvalues of a matrix A = x \ocross x, where \ocross is the outer product, but without having to compute A (can be quite large).

median tendon
#

What other forms can we use it on?

vale wigeon
#

1/x is not defined for all real x. your example does not work.

tough hatch
#

you can't use lhopital's in the first place if f or g is not differentiable, lol

vale wigeon
#

(II) is not true. take f = 0 and g = any discontinuous function you want

median tendon
#

Ann i think he was providing an example to show that II was wrong

pearl marlin
#

Take sinx and 1/x

vale wigeon
#

learn4math, 1/x isn't defined for all real x.

#

you cannot have it be one of the functions for the purposes of this problem.

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@dusk wedge sorry, this channel is busy right now. please move to a different questions channel or #linear-algebra.

pearl marlin
#

Ops i made mistake

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G is not continuous every where

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Apology

dull onyx
#

are u guys still using this channel

tough hatch
#

apparently not

leaden thicket
#

can anyone help me for this question please with solution

sage bronze
ocean sealBOT
#

HELLOBELLO

leaden thicket
#

than?

slate heron
#

do you know how to subtract fractions?

leaden thicket
#

ya i think

sage bronze
#

$\frac {tan^2 (x) - ((sec(x) \times (sec(x) +1)}{(sec(x) +1)}$

ocean sealBOT
#

HELLOBELLO

wild marten
ocean sealBOT
#

Beluga

sage bronze
#

@wild marten

wild marten
#

I just gave a hint above

sage bronze
#

Ok

wild marten
#

oh wait, it does not work like that, answer could be -1 or tan^2(x) - sec(x)

#

@sage bronze

wild marten
#

yeah, but its confusing. According to your bracket placement it is tan^2(x) - sec(x)

fleet marsh
#

should i be solving the de with separation of variables and then setting that solution equal to the kx*arcsin(x) expression and solve for k?

vale wigeon
#

no you're way overthinking it

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just plug in y = kx arcsin(x) into the DE and solve for k

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@fleet marsh

fleet marsh
#

omg

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right

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tyvm

wild marten
#

check my about

leaden thicket
#

Oh

ancient bear
#

Why do we write Ax + B and Bx + C instead of A and B like with the case of linear factors?

#

Is it because it's one degree lower...

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Huh

surreal meadow
#

because B may not equal C

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wait i misunderstood the question

#

Ax + B and Cx + D
instead of
Ax + B and Bx + C

tough hatch
#

which would indeed result in having not just the same denominator for both fractions but also a third-degree polynomial in the numerator

ancient bear
#

ohhh

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in other words

#

so that these when multiplied give us the 3rd degree polynomial that we see on the left

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got it, thanks

hardy vault
#

can someone help me

tough hatch
#

you still have to add the (now similar) fractions

ancient bear
#

yes, I know, but adding them won't change the degree

tough hatch
#

not necessarily, at least

crystal steeple
#

hey fellas

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im kinda dumb

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but i need to find x

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this is the last step

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and heh

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im asking in a diffrent channel

tough hatch
#

@crystal steeple btw stick to one channel lol

#

ok lemme help you with that

crystal steeple
#

oh ok

tough hatch
#

do you know how to deal with logarithms?

crystal steeple
#

yeah

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but no matter how i try i cant do this

tough hatch
#

can you rewrite that equation as a logarithmic one?

crystal steeple
#

no.....

tough hatch
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for example

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2^x = 4

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how do you turn this into a logarithmic equation?

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log_base (result) = exponent/missing power

crystal steeple
#

ok so once i turn this into log

tough hatch
#

can you?

crystal steeple
#

yeah

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i can

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i did

tough hatch
#

so write it out here

crystal steeple
#

this?

tough hatch
#

no

crystal steeple
#

oh

tough hatch
#

is 8/10 the exponent of 9/10?

tough hatch
crystal steeple
#

OO

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OK NVM

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THNK U

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but how do i put it in a calculator

glass lichen
#

If you have a log base button... or change of base

crystal steeple
#

im using casio 570 ms

tough hatch
#

find the button named log

crystal steeple
#

yeah found it

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@tough hatch

plucky crow
#

the direction vector AB is -3, 5, 10

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right

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so for part c

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c + ab = d

tough hatch
plucky crow
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oh its taken

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my bad

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ill wait

crystal steeple
#

i clicked the log button

tough hatch
#

lol no need to ping me

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ok

#

channel is free

plucky crow
#

@crystal steeple if you do 2^log2 it cancels,

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so just use that logic

tough hatch
#

they just wanted to notify me.

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i digress

cosmic geyser
#

smallest whole number than be split into 25%, 35% and 40% (whole number)

fluid ember
#

20

wispy olive
#

Can we? If yes, then how? If no, then why?

topaz scaffold
#

Yes

amber urchin
topaz scaffold
#

For the second one use Herons formula

#

Or actually just use Pythagorean theorem

vale wigeon
#

it's ||impossible. imagine dragging the apex of the triangle parallel to the base as far as you want in either direction; the height stays the same, and so does the area, but the perimeter can be made arbitarily large||

wispy olive
#

Heron's Formula?

topaz scaffold
#

Oof

vale wigeon
#

heron's formula lets you find the area of a triangle in terms of its sidelengths

topaz scaffold
#

My brain ain't working, sorry

vale wigeon
#

it's somewhat unwieldy unless it really is all you have to work with

wispy olive
vale wigeon
#

which big words?

tough hatch
#

triangle wasn't given to be a right triangle

amber urchin
#

I dont think you can find perimeter, knowing only 1 side and 1 altitude

wispy olive
#

Yeah exactly.

topaz scaffold
#

Yea you cant

wispy olive
#

But maybe I can.

vale wigeon
#

which big words, senku ishigami?

wispy olive
#

No?

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Reason/s?

wispy olive
topaz scaffold
wispy olive
#

Apex, arbitarily large.

vale wigeon
#

i am happy to explain what i meant, but i do not know which part(s) of what i said you don't understand.

amber urchin
wispy olive
vale wigeon
#

"apex" in this case just means the vertex opposite to the fixed-length side.

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i.e. it's the vertex from which you would drop the altitude.

vale wigeon
#

"arbitrarily large" means "as large as you wish" or "larger than any number you could give me"

wispy olive
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You have to make another point for it in 1 of the sides on the triangle?

vale wigeon
#

what?

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what are you talking about?

wispy olive
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Les say

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Triangle ABC.

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And les say

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We take the height from angle A.

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So it has to land somewhere on angle BC.

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So that point.

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Will be the apex?

vale wigeon
#

there's something to be noted here

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the altitude need not land on the side BC itself

wispy olive
#

Woah this is SICK!!!!

vale wigeon
#

it is extended until it meets the straight line which contains BC

wispy olive
#

But big :|.

vale wigeon
#

that is how you determine its length

vale wigeon
#

here is an illustration, albeit using different notation than you.

wispy olive
#

Hmph?

vale wigeon
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dragging C along this horizontal line will not affect the area of the triangle, no matter how far you go

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however, the perimeter of the triangle will increase, as should be obvious.

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also, regarding heron's formula

wispy olive
#

Would not it be this line?

wispy olive
#

?

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Sorry I am dumb.

vale wigeon
#

yes, what you have drawn is an altitude.

wispy olive
#

Oh.

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LMFAOO you just agreed that I am dumb.

vale wigeon
#

here is what an altitude may look like for a very 'stretched-out' triangle, for lack of a better word.

leaden thicket
#

can you please help

wispy olive
#

Wow you were so smart in 8th grade then @vale wigeon ?

vale wigeon
#

eh?

leaden thicket
wispy olive
#

Noice.

amber urchin
#

I dont remeber what exactly sin(90-A/2) is, but there may be a table on which one would that be

vale wigeon
leaden thicket
#

a/2 is in all options

wispy olive
#

But you agreed that I am dumb.

vale wigeon
#

i didn't??

amber urchin
leaden thicket
wispy olive
#

So I interpret from that information that you were very smart and intelligent when you were in 8th grade.

leaden thicket
#

sin(90-x) = cos (x)

wispy olive
amber urchin
wispy olive
#

Anyway.

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This is not the point.

vale wigeon
#

the "yes" does not apply to your calling yourself dumb.

wispy olive
#

Just appreciated you anyway.

vale wigeon
#

if it did, i would have said "yes, and what you have drawn is an altitude"

leaden thicket
vale wigeon
#

but the lack of this and changes the meaning of my sentence enough to make it so that i take no stance at all on your dumbness, senku.

wispy olive
#

Wow.

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Serious grammar.

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I do not mind anyway bruh.

pallid sail
#

gamer even if she meant it u shouldnt get offended

#

this is the internet

wispy olive
#

Yeah exactly.

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That Is why I said.

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I do not mind anyway.

pallid sail
#

like anonymity allows people to say whatever they want

wispy olive
#

And I am dumb, even I know Lmfaoo.

vale wigeon
#

i don't appreciate having words put in my mouth, i will say that much

wispy olive
#

Sorry Ann.

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I will just ask normal questions from now.

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Thank you for the help.

plucky crow
#

1 mark??

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i did it using the cross product

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since its 1 mark there must be an easy way to do it right

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that im missing

surreal meadow
#

yes, using the cross product

plucky crow
#

is there no other way

gray isle
#

consider certain properties of a parallelogram

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and you should be able to get the area from something you obtained earlier

plucky crow
#

oh

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hahaha

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yeah i see

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now

surreal meadow
#

did you do the area of the parallelogram/2 for part b?

plucky crow
#

no i did 1/2ab sinc

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and i found the angle c using the dot product

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truth is the cross product isnt even in my course xdddddd

tough hatch
#

they just gave u what u need lol

plucky crow
#

yes i realized that

fading solar
#

Please tell me
Sec theta + tan theta =x, then what is relation of sec theta - tan theta in terms of x

leaden thicket
topaz scaffold
#

You could add the 2 equations to get that 2 sec theta = 2x

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Oh shoot nvm

fading solar
topaz scaffold
#

Dont do that

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There's an identity that's pretty close to the equation

fading solar
#

Tan^2 theta + 1= sec^2 tbeta

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*theta

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But i am not getting the answer

topaz scaffold
#

Yep

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Use difference of squares

fading solar
#

Okk

alpine sable
#

Can somebody help me on this one?

#

I need to find the vector which is a linear combination of x1, x2 and x3

alpine sable
#

UP

lusty plaza
alpine sable
#

i computed all the combinations of x1, x2, x3 and the other ones in an online calculator, and all of them are linearly dependent

lusty plaza
#

surely your textbook or teacher taught you a method for finding linear cominations of vectors?

lusty plaza
# alpine sable im studying on my own

Please support my work on Patreon: https://www.patreon.com/engineer4free

This tutorial goes over how to determine if one vector is a linear combination of a set of vectors. It is part of a full free course on linear algebra.

Links:
All Free Linear Algebra Tutorials (Website): https://www.engineer4free.com/linear-algebra
All Free Linear Algebra...

▶ Play video
winter mango
# alpine sable

i cant figure out a way to do this without just trying all the combinations in the answers

#

and seeing which ones don't have contradictions

weary hazel
#

??

winter mango
#

maybe you can do a matrix with a determinent of 0?

glass lichen
#

the co-efficient matrix will have det of 0 by FTIM since it's somewhat implied {x1,x2,x3} isnt a basis of R^3

alpine sable
#

ohh got it

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x3 is a combination of x1 and x2

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then i can do a matrix with x1, x2 and the other

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since x3 was the linearly dependent term, it was obscuring the result

winter mango
#

yeah

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3*3 matrix which seems more solvable

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determinant 0 and solke mb?

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solve*

alpine sable
#

Answer is letter C

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All the others span R3, so they are independent, and only C spans R2, so it is dependent

winter mango
#

@alpine sable you have the solution on paper?

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like with the method and stuff, wanna practise some vector stuff

alpine sable
#

hold up

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I just tested all matrices until one was = 0

winter mango
#

ye

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was wondering if there was like

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a more systematic solution

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like using a b c as the third vector

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but this is simple enough

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thanks my dude

alpine sable
#

To find the dependent vector you could make a system with the 3 eq if you didnt figure out just by looking

winter mango
#

sounds reasonable

alpine sable
north goblet
#

i have this issue. gotta find AD lenght.
It's not that hard as a problem i think but don't remember the formulas or the theory.
Anyone knows what can i look up for ?

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i don't even know what to look for tbh

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maybe doing a proprotion with the angles ?

wary stream
#

And that is not the best way to denote 90 degress

north goblet
#

Ofc is not to scale as it doesn’t really matter

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As well as u denote the 90degrees

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How that even matter ? Lol

wary stream
north goblet
#

ADB is 45•

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Mb

wary stream
north goblet
#

ok, can u help me with the data btw ?

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or just wanted to act smart ass ?

wary stream
#

I had to get it the correct info first

north goblet
#

so, what can i look up for ? what formulas ?

unborn dome
#

can someone help me out with this question?

#

i know one of the answers is 6arcsin(5/8) / pi
but I'm not entirely sure how to get the second answer, do I just do the same thing but 6 - 6arcsin(5/8) / pi to have arcsin by itself?

obsidian cave
ionic jewel
obsidian cave
#

Actually, the triangle is 90° 45° 45°, it's isosceles, AD = AB

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Yeah what they said

unborn dome
#

uh should i take my question to another channel?

unborn dome
#

gotchu

wary stream
#

An inactive channel

north goblet
#

ok let's do a step back because in scale u can see what i mean

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difficult

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to write on pc

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draw*

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the scale is around the height being 6 times the base

wary stream
#

Since triangle ABD has a right angle and angle ADB is 45, you can conclude that angle ABD is also 45

#

Therefore making it isosceles

vital sleet
#

If you are using chain rule here

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what happened to the tan in the 2nd time differientating the inside?

wary stream
vital sleet
#

oh wait

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this isnt inactive

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mb

north goblet
#

u cannot conclude that what the heck

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u can even see it

wary stream
#

Yes you can

north goblet
#

all right i understand gonna move to someone that knows what is talking about

wary stream
#

Sum of angles in a triangle equals 180

unborn dome
#

woah

vital sleet
unborn dome
#

@north goblet calm down, all you do is play arknights man

#

we gotta evaluate math step by step

wary stream
#

So 180 - 90 - 45 = 45, therefore ABD is 45 degrees

wary stream
obsidian cave
#

Not to make anything bigger than it is but it's so funny to me that a person joins a math help server, gets told a triangles angles sum to 180, then just denies it and leaves

unborn dome
#

@obsidian cave what do you mean the earth is obloid and not flat? blasphemy I say

frail gulch
#

lmao what is going on in this channel

ripe mountain
#

How do you make a 3d function of 2 variables that has at one point a minimum in one direction and a maximum in another direction

thorn kindle
unborn dome
#

lmfaoo

thorn kindle
#

Or it can vary actually. It just has to be greater than 180

#

Angle sum on a sphere is 180(1+4f) where f is the ratio of the enclosed surface area to the area of the sphere

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So if f is small it approximates euclidean geometry

thorn kindle
#

log_a(b) = log(b)/log(a)

nova heart
#

okay, i feel like this should be easy but im so confused
i've got a table of user's percentage who use certain programming language
how can i know the given population out of it?
for example c++ is used by 12%, c# by 3% etc etc

ionic jewel
#

if you know the total population you can just multiply it by the percentage

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eg if 150 people took your survey, 150*0.12 use cpp

winter token
#

I am not sure if high school level stuff is allowed here but I need some help with this!

I need to find the inverse function of this, but I have trouble solving it for x... Can somebody help me?

jagged imp
#

high school stuff is most of what populates these channels so its definitely allowed

#

what have you tried so far?

ionic jewel
#

x = ln(e^x)

#

may help to condense into one log

winter token
#

I played around with properties of logarithms and exponents to see if I could get anywhere but I keep getting stuck...

I simply rewrote the function in different ways like

e^y = (e^x)/ (e^x-1)

And much much more forms that wouldn't help me get anywhere

ionic jewel
#

,w inverse of y = x - ln(1+e^x)

winter token
#

I'm convinced that wolfram alpha is wrong here, If you put both functions at desmos you can tell that is not the correct inverse

ionic jewel
#

,w simplify e^x/(1+e^x)

ionic jewel
#

ah there we go

winter token
#

According to my book the correct answer is f(x)=ln(e^x/1-e^x)

ionic jewel
#

this only has one variable, and should be easy to invert

#

i knew that simplified somehow

winter token
#

but I can't myself get to that

ionic jewel
#

divide each term by e^x

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once you get them all in one log

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$y = \log\frac{e^x}{1+e^x}$

ocean sealBOT
ionic jewel
#

multiply the fraction by e^(-x)/e^(-x) to get what Wolfram gave you for simplification

#

can you get the rest @winter token

winter token
#

Hope so, wish me luck :Ρ

ionic jewel
#

i can latex it all out if you need, ping if you do

winter token
#

latex?

ionic jewel
#

the typesetting

ionic jewel
winter token
#

That would help yeah

#

I am just kind of lost on where I start in this I don't need the entire procces

ionic jewel
#

okay one sec

winter token
#

$e^(x-y) = 1+e^x$

ocean sealBOT
#

-KlariNoX-

ionic jewel
#

wait what is this

winter token
#

This is as far as I got, (x-y is an exponent)

ionic jewel
#

i dont think we want this

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no we dont

#

ok here we go

#

Original thing is
$$y = x - \log(1+e^x)$$
right?

ocean sealBOT
winter token
#

yes

ionic jewel
#

do you agree that is equal to
$$y = \log\frac{e^x}{1+e^x}$$

winter token
#

I need to solve that for x to find the inverse function

ocean sealBOT
ionic jewel
#

using log rules

winter token
#

Uhh... which rule is being used here?

ionic jewel
#

$x = \log(e^x)$, then using that $\log(a) -\log(b) = \log(\frac ab)$

ocean sealBOT
winter token
#

ohhh thats genius

#

yeah I realised what you did now

#

I think I got it from here, Thank you so much!

ionic jewel
#

okay now we want to simplify our $\frac{e^x}{1+e^x}$ by multplying it by $\frac{e^{-x}}{e^{-x}}$ to get $$\frac1{e^{-x}+1}$$

ocean sealBOT
ionic jewel
#

ah this step there is a tricky one too ^

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but alright, perfect

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lmk i fyou dont

winter token
#

@ionic jewel I was able to solve it, though I have to admit I probably wouldn't have if you didn't show me how to simplify that fraction in the last text 😅

Thanks a ton for the help! I've been scratching my head for hours on this problem

ionic jewel
idle stratus
#

[Laplace transforms, Control Theory, Electronics] I'm trying to figure out why I need to subtract LsI_2 in eq1 and LsI_1 in eq2. It looks like I_2 doesn't run through the inductor why do I need to subtract it?

wary stream
past sundial
#

Can someone explain tan to me? (Imma move this to a diff channel cause there’s a discussion I realize)

idle stratus
#

actually I got it... it makes sense because I1 and I2 are closed loops which I didn't think they were

wary stream
arctic delta
#

is my math right here?

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im fairly confident but at the same time i couldve overlooked something

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<@&286206848099549185>

astral dagger
#

look at your second line, the implicit derivative is wrong

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try to fix it

arctic delta
#

you mean the cos?

astral dagger
#

also the cos, I didn't understand if it's argument is a x

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of if I'm seeing things

#

but more specifically the h/4600 derivative

arctic delta
#

what's wrong with it? seems right to me, dh/dt is the speed of the rocket

oak chasm
#

h/4600 = 1/4600 times h.

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What's the derivative of h?

arctic delta
#

the speed

oak chasm
#

No, what's the derivative of the variable h?

arctic delta
#

hmm

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well that'd be the derivative of h(t) then right?

oak chasm
#

It's dh/dt.

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So, it's 1/4600 dh/dt, not h/4600 dh/dt.

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That's one error.

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The other error is you have tan(theta).

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Somehow theta becomes x.

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The derivative of tan(theta) is sec^2(theta) dtheta/dt.

arctic delta
#

ah somehow changed that

astral dagger
arctic delta
#

deriv of tan theta is also 1/cos^2

ocean sealBOT
#

SubGui

#

SubGui

arctic delta
#

so something more like this?

#

also i did forget to do pythag for sec/cos theta last time just realized

oak chasm
#

Yes, except minor error, the cos^2(theta) is missing the closing parenthesis.

arctic delta
#

gotcha

oak chasm
#

@green cave I'm not sure this channel is open. Try #help-9.

green cave
#

oh srry will do

arctic delta
#

okay here's the revised version

#

the number does makes more sense in terms of the question

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@oak chasm how's this

oak chasm
#

You can't get 0.75 from a number about 1/7 times a number less than 1.

#

Also, it's probably radians instead of degrees.

arctic delta
#

well that part is about 0.147

oak chasm
#

You're going to get a number close to 1/7 times 7/9 or 1/9.

arctic delta
#

well idk what i did wrong considering those are the correct numbers

#

maybe i could change the unit to radians

#

instead of degrees/sec

oak chasm
#

,calc 68/460 * 2116/2792

ocean sealBOT
#

Result:

0.11203438395415
arctic delta
#

680 not 68

oak chasm
#

Yes, 680/4600 = 68/460.

arctic delta
#

oh right

oak chasm
#

So, 0.112 radians per second.

arctic delta
#

im in radians and i get 0.14

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odd

oak chasm
#

How did you get 0.14?

arctic delta
#

wait a sec

#

okay i got that number

oak chasm
#

,calc 68/460 * 2116/2792 * 180/pi

ocean sealBOT
#

Result:

6.4190973609213
oak chasm
#

6.42 degrees per second.

arctic delta
#

thanks, turns out i forgot to multiply the two numbers and the 0.75 comes from the 2116/2792

#

can't believe i made that mistake

native temple
#

this open

#

?

arctic delta
#

yes

native temple
#

I’m learning about toolkit functions never heard of it

#

What are they

#

(via self studying a pre calc testbook)

vale wigeon
astral dagger
#

you also could use #precalculus to debate some more if someones interested

#

then you open this channel to another questions

native temple
#

At least to get the basics in

astral dagger
vale wigeon
#

this feels like a really non-sequitur reply

native temple
vale wigeon
#

lmao

#

what a coincidence

#

it was the first google hit

#

but yes self-studying math is good i guess???? it depends heavily on what youre studying from

native temple
#

openstax pre calc textbook

native temple
#

I understand learning from a course(a textbook is a course in book form)

#

Depends on how good the course is

#

and how much human feedback you have

#

(mine is from here…..)

#

but this is the information I have

floral willow
#

I have gotten to the stage where y/2x = 1

#

but can you tell me what the math principle is for this?

#

Not the answer, just what it's called.

#

I want to solve this myself as I'm sure it's not difficult

placid zinc
#

Good luck with it

floral willow
#

But what is this called?

vale wigeon
#

a good chunk of algebra is governed by the same principle

#

"do the same thing to both sides"

#

in your case, you can multiply both sides by something to progress towards the solution.

floral willow
#

but that doesn't help.

vale wigeon
#

you are familiar with "do the same thing to both sides", yes?

native temple
#

what does in terms of n mean?

#

I can’t help this person unless I know what that means

floral willow
#

The issue is that y numerator.

vale wigeon
#

'solve for x in terms of y' means the same as solving for x, except that the answer will be an expression involving y rather than just a number @native temple
but also you don't need to interrupt

#

@floral willow well why not multiply both sides by something?

native temple
#

okay

vale wigeon
#

say, multiply both sides by x?

#

you may be surprised at the outcome.

floral willow
#

Yes, I understand, but I'd like to read a link about it.

native temple
#

give me a minute

floral willow
#

I can't find it in Google.

#

It will stick better if I have a guide to fall back on.

vale wigeon
#

mm

#

i cant think of any guide to give you here unfortunately

#

this is the sort of stuff you learn by doing rather than by reading

floral willow
#

hmm, there must be some guide about this type of problem.

#

I mean, I already have the solution, but that doesn't help me if I don't understand the mechanics of the problem.

placid zinc
#

Imagine telling me to delete my hint, when they have the full solution in front of them 🤣

floral willow
#

Well, I was trying not to look at it, but since no-one is aware of any guides for this, I felt I had no choice.

#

But I did try not to look at it and solve it on my own.

placid zinc
#

"Rearranging algebraic equations" is the lesson title

floral willow
#

ok, let me try to google that, one sec.

placid zinc
#

Yes that's similar

floral willow
#

What specific link were you referring to?

native temple
#

Here’s how to solve step my step

#

the principle of algebra is the golden rule

#

to do operation $n$ on $ Expression A$ do operation n on all sides of expression a

ocean sealBOT
#

Nerdy_Coder

native temple
#

in other words simply do operations on all sides

#

like with fractions

#

to convert s fraction to it’s equivalent operate on both numerator and denominator

floral willow
#

I think what I was missing was this rule:
RULE #2: to move or cancel a quantity or variable on one side of the equation, perform the "opposite" operation with it on both sides of the equation.

native temple
#

oh

floral willow
#

Next is this -> "Solve for x in terms of y"

#

I think I can feel how to solve this problem, but I don't know how to explain what it means.

#

I'm trying to search for a link now.

#

thank you for the help!

faint steeple
#

hello!

#

I just want a sanity check, is this correct? my solution is in red

dusk schooner
#

hey i need a help for my assingment can someone help?

ionic jewel
#

,w complex conjugate of (z-i) = 6-2z

dusk schooner
#

,w If 5sinA = 4, then find the value of 5cosA

#

??

faint steeple
#

so my solution was wrong D:

oak chasm
#

@dusk schooner Sorry, this channel is busy. Try #help-6.

dusk schooner
#

dont ping

faint steeple
#

because I've clearly gotten

#

not sure how Wolfram went from that to z = 2-i

vale wigeon
#

what is x?

#

are you implicitly saying z = x + yi?

faint steeple
#

that's basically what I was trying to do yeah

vale wigeon
#

well then do it in full

#

2x + z + i = 6

#

2x + x + yi + i = 6

#

3x + (y+1)i = 6 + 0i

faint steeple
#

is implicitly saying z = x+yi incorrect?

#

I was just going off my notes which says that z* + z = 2x

#

based on a conjugate of x+iy + x - iy = 2x

dusk schooner
#

The abscissa of the point R that divides the line joining the points A(2, 3) and B(7, 3) in the ratio 3:2 is???

vale wigeon
#

@dusk schooner channel busy please move

dusk schooner
#

aight

vale wigeon
#

@faint steeple if you introduce the variables x and y for the real and imaginary part of z then you have to do so explicitly

#

otherwise nobody will know where this mysterious x comes from or what it has to do with z

faint steeple
#

ah, I see...

#

let me go back and try my solution again with explicit declarations then

#

and also in full as you said

#

thanks 🙂
may be back in a bit if I need help

#

channel's free now

rich basin
#

what is this

#

It is neither of them

#

I am really confused

misty pebble
#

Given that 0 < a < 360, then the equation sin(a) = cos(a) has how many solutions? How would I work this out?

green cave
#

||45°,(180+45)°||

green cave
slender marten
#

Convert the problem into an equivalent problem, we may divide by cos(a), where cos(a) is non-zero. Then we can answer the equivalent question tan(a) = 1 on the interval 0 degrees <a < 360 degrees.

misty pebble
#

Would it then be four? It's equivalent in four spots

green cave
misty pebble
#

Oh, 2?

proud estuary
#

How do I solve this, not the answer, just how do I figure it out?

gray isle
#

first consider setting up a fraction

slender marten
#

Understanding that billion is 10^9 might help.

gray isle
#

then express 75billion in scientific notation
and apply exponent laws

proud estuary
#

I appreciate it but this is a question for my daughter and I have no clue how to even work it or what you guys mean, can you explain the steps?

vale wigeon
#

do you know what 'scientific notation' means?

#

(do not be afraid to answer no)

proud estuary
#

no

vale wigeon
#

ok, let's back up further

#

do you know your way around exponents?

proud estuary
#

nope sorry, like I said all of this is new to me.

vale wigeon
#

wait so...

#

even this

#

is foreign to you?

proud estuary
#

yes foreign to me sorry, like I said trying to understand to help my daughter.

vale wigeon
#

it would be a lot better if we could get your daughter on the line, but i suppose she may be too young

#

this is going to be very difficult

#

because you would basically need to learn about exponents before even beginning to approach this problem, as understanding scientific notation is impossible without understanding exponents.

proud estuary
#

any explanation is appreciated.

#

thank you anyhow

vale wigeon
#

trying to think about where to begin explaining this...

slender marten
#

I think you should direct this to a teacher or something.

#

There's only one way for you to be able to do it, learn maths yourself. I can give you resources but it will take you a long time, more than you are willing to commit, assuming we're not being trolled.

proud estuary
#

True but her teachers are not available. but again ty

vale wigeon
#

khan academy is decent for learning basic stuff like this. the key words are "exponents", "exponent laws" and "scientific notation".

slender marten
vale wigeon
#

she may well be 11 or 12.

slender marten
#

They don't teach nothing in the UK then, I didn't see that till college (16-18 years old).

ionic jewel
#

I definitely learned scientific notation in middle school, so something like 11-13 sounds about right

#

but it was in some sort of intro to science class or something, not in algebra iirc

slender marten
#

(I told you, they don't teach nothing in the UK, what is going on.)

#

Maybe they did and I just forgot.

green cave
frail gulch
#

Exponents are a shorthand way of writing "i want to multiply something by itself N amount of times". For example, 2^4 is the same as 2x2x2x2 which is 16.

#

On an unrelated note, its hard for us to comprehend really large numbers quickly. For example, if I told you to multiply 10 million by 20 billion, how could you do this in your head?

#

One way to do this is to try and write large numbers in a shorthand, easy to understand method, usually with some estimation and "rounding". 2,345,678 could be estimated as 2,300,000 which is the same thing as 2.3 x1,000,000 (2.3 million)

floral willow
#

If you don't understand that, then start at the very beginning of the math section.

#

It starts with 1+1 = 2, I think.

frail gulch
#

If you notice something about multiplying by 10s, each time you multiply by 10 you simply add a 0 to the end of the number. So 1,000,000 has 6 zeroes, and is thus equal to 10x10x10x10x10x10, or also 10^6.

#

If you convert large numbers to this kind of format, it makes dealing with large numbers a lot easier. That last time about 10 million x 20 billion? Its the same thing as 10^7 x 2 x 10^10, and now you can simply count the number of 10s and get the answer of 2×10^17.

proud estuary
#

ty all for trying to help, I am going to take your advice and look at khan.

frail gulch
#

Good luck!

floral willow
#

Khan is good enough for beginners from what I've seen so far, although it would be much better with real world applications. But then again, there are hardly no textbooks that cover real world applications. Anyway, be sure not to skip around, as the concepts build upon each other.

#

Is the second variable numerator a fractional exponent?

wary stream
ocean sealBOT
#

dldh06

floral willow
#

Hmm, I'm not sure how to write it.

ionic jewel
#

$v^2_0$

wary stream
#

That's a v with a subscript zero, known as naught

ocean sealBOT
wary stream
#

So v naught

ionic jewel
#

oh is that how you spell it lol

wary stream
#

Yep

ionic jewel
#

i always though it was v not

#

lol

wary stream
#

,w naught

floral willow
#

Hmm, I'm not seeing any results for this on Google.

wary stream
#

It's just a variable

#

$v_0$ is a variable

ocean sealBOT
#

dldh06

floral willow
#

I don't know what to do with it.

#

What do I search in Google to research this math process?

#

I tried "v naught", but it showed Physics.

wary stream
#

Because it is physics related

#

But treat it like a regular variable

#

Like $y^2$

ocean sealBOT
#

dldh06

floral willow
#

Hmm, this is confusing, but let me try.

wary stream
#

It's just a variable, that's it

floral willow
#

I'm stuck at:
$v^2_0$ = 1/-5x_0$

ocean sealBOT
#

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

wary stream
#

What happened to $v^2$?

ocean sealBOT
#

dldh06

floral willow
#

Oh, wait.

#

I'm stuck at:
$v^2 + v^2_0$ = 1/-5x_0$

ocean sealBOT
#

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

wary stream
#

Like I said treat $v_0$ as a variable

ocean sealBOT
#

dldh06

wary stream
#

So like $y^2$

ocean sealBOT
#

dldh06

floral willow
#

I still don't get it.

#

Any links to other examples, maybe?

#

Or at least the name of what this part of math is.

#

I know it's "v naught", but that doesn't yield results in Google.

wary stream
#

If you had $v^2 + y^2 = \frac{1}{-5x_0}$, how would you solve for v?

ocean sealBOT
#

dldh06

wary stream
floral willow
#

let me try the example you just posted

wary stream
#

The example I posted is exactly the same as what you have, I just used a different variable

wary stream
ocean sealBOT
#

dldh06

wary stream
#

That's wrong

floral willow
#

The opposite of $v^2$ would be the square root, yes?

ocean sealBOT
#

Willow

wary stream
#

Yes

floral willow
#

Does that fall under the Law of Exponents?

wary stream
#

Not sure what that's exactly called

floral willow
#

I don't know how I remembered that either. But I'd like to update my notes.

#

Hopefully, someone comes along that knows what its called.

wary stream
#

It's just known that the opposite of squared is square root

jovial forum
#

What's actually happening when we 'eliminate the third column'? I really don't get this (trying to put something in RREF for Linear Algebra)

wary stream
#

I mean, you can apply law of exponents for that

floral willow
ocean sealBOT
#

Willow

wary stream
#

Where's the y?

floral willow
#

I don't know what happens to it.

#

but one second please, an additional video resource was just posted to us students.

#

I'm going to try and watch it to see if it helps me understand.

floral willow
#

On this problem

#

Not your problem, but the original problem I posted

#

I guess other students were also confused

#

let's see if it helps

wary stream
#

Like I said, those are just variables

tepid jungle
#

Does this mean that the probability of X1, X2,.... of occurring is p?

#

and that the distribution is geometric?

noble sinew
tepid jungle
#

but isn't p of a geometric distribution the probability of success

#

@noble sinew

noble sinew
#

It is

tepid jungle
#

oh pr of success, the Xn is just each variable, which could be anything

#

thank u

mortal void
#

Using variables and operation symbols, express each of the following verbal statement

#

The product of two successive odd number is 35

#

someone help me with this, my tiny brain is so confused

noble sinew
mortal void
#

but i am not getting the numbers with solving this!!

noble sinew
#

Why not

#

How are you solving it

vale wigeon
#

what are you getting?

mortal void
#

this

vale wigeon
#

so you got x=5 and x=-7 as potential solutions.

#

that is correct.

mortal void
#

or am i doing it wrong

vale wigeon
#

the numbers which multiply to 35 are x and (x+2), as you should remember from the equation you wrote yourself.

noble sinew
#

Then the other number is just x+2 like we said

#

And you are done

mortal void
#

how can we put if on the equation tho?

vale wigeon
#

what do you mean?

noble sinew
#

You found x=5 is a solution - then the pair {5,7} is a solution for example

mortal void
#

okay so we put one at one time lol sorry

vale wigeon
#

you used the letter x for the lower of the two numbers you're multiplying

#

the other number is x+2

#

you should have understood this much when writing the equation

mortal void
#

i was getting confused cause i was thinking to put both of them at once

alpine sable
#

Hey

vale wigeon
#

find two different paths, with the same start and end points, such that the integral of F · dr along one path is not the same as the integral of F · dr along the other path

limpid aurora
#

yeah the part im stuck with is i don't know how to find two different paths

limpid aurora
vale wigeon
#

@native cloud channel busy please move

#

@limpid aurora you have a lot of wiggle room here lol

#

pick any two points you like, literally any two points

#

and connect them with two different paths

#

you might, for example, go with the straight-line path

#

or a three-segment path which first goes parallel to the x-axis, then parallel to the y-axis, then parallel to the z-axis to get from the first point to the second

#

those are just some examples of the possible paths you could take

#

don't overthink it basically

limpid aurora
#

ahhh ok

#

thank you

#

i think the problem is i can't visualize this lol

vale wigeon
#

do you want me to get you started with some example paths

limpid aurora
#

yes pls

vale wigeon
#

take A = (0,0,0) and B = (1,1,1)

the straight line path from A to B: r(t) = (t, t, t) where 0 ≤ t ≤ 1
the 'parallel to axes only' path from A to B: r(t) = (t,0,0) for 0 ≤ t ≤ 1; (1, t-1, 0) for 1 ≤ t ≤ 2; (1, 1, t-2) for 2 ≤ t ≤ 3
a twisted path: r(t) = (t, t^2, t^3) where 0 ≤ t ≤ 1

#

please note that you do not need to take these exact paths. if you think you can see a path that makes calculations easier, then by all means go for that instead.

#

and don't overthink it.

limpid aurora
#

ohh ok that makes sense

#

thank you!

alpine sable
alpine sable
#

wait

gray isle
#

you're conflating the zero product property

alpine sable
#

hmm

#

so how to find values of x

gray isle
#

ab = (something that isn't 0)
doesn't necessarily mean that a = that something or b = that something

alpine sable
#

oh lol

#

yeah

#

true

gray isle
#

well you have a quadratic equation, (you could solve that using appropriate methods)

#

however

alpine sable
#

yes

#

mb

gray isle
#

since you're looking for consecutive odd numbers,

#

you should be able to find the solutions relatively easily in that form from the factors of 35

alpine sable
#

using complete the square is also another way ,ig

#

alright got the right answer, thx for pointing out my mistake

turbid harbor
#

anyone know how I can start this question? It was in our end of year exam (first year robotics) and i had no idea how to start it as you cant seperate the variables to diff sides easily?

#

i obviously gave it a full page try but looking back through notes i dont think you can just open up with a divide by tan x llol

#

hm maybe I could subtract y then factorise the right as y(2secx-1) ?

#

and divide by (2secx-1) might go try that while waiting for a tip here 😄

#

ok i definitely can't do that 😂 typing without thinking...

#

feck this question 😂

wise sigil
#

@turbid harbor Try multiplying the equation by cos x

turbid harbor
#

shall do 😄 ty

#

tanx is sinx/cosx no idea how this is gonna hellp but i trust you 😂

#

ooo ok

#

clever

wise sigil
#

Got it then?

turbid harbor
#

i think so TY 😄 definitely got a route to go down

alpine sable
#

Are you guys finished?

turbid harbor
#

i am not super experienced with trig identities tbf and dont jump to them

#

yes

#

🙂

alpine sable
#

I need to ask a question

#

I think i might have messed up

turbid harbor
#

that means you're learning 😉 shoot the question

alpine sable
#

I needa find the gradient for these

#

(1,2) and (3,6)

turbid harbor
#

the equation for gradient is m=(y2-y1)/(x2-x1)

alpine sable
#

ye

#

2-6/2-3

#

Correct?

turbid harbor
#

(1,2) and (3,6)
x1y1 x2y2

#

i think you got your x1 and x2 wrong

alpine sable
#

6-2/3-1

turbid harbor
#

yes i think 😄

alpine sable
#

Lmao i got confused with my

#

x1 and x2

turbid harbor
#

change in Y over change in X is an easier way to remember it imo bc then you know you need to subtract the ys and xs without looking at weird symbols like y2y1 😛

turbid harbor
alpine sable
#

Gradient is 2

turbid harbor
#

you got it 😄

alpine sable
#

@turbid harbor let’s try with one more

turbid harbor
#

then try again in a day or 2 and in a week and a month to drilll it into your long term memory 😉 (something im bad at personallly but working on)

alpine sable
#

2,3 and 6,8

#

alr so

#

8-3/6-2

#

5/4

#

@turbid harbor correct?

turbid harbor
#

looks it bro! im a lowly first year uni student who did A levels 8 years ago and only brieflly touched on this stuff in first year 😛

#

so dont take my word as gospel, but yeh pretty sure you got it

alpine sable
#

Lmao im yr 9

turbid harbor
#

you could always use an online checker to double check your answers

alpine sable
#

And i keep being confused in the arrangements

turbid harbor
#

impressive mathsing like this in year 9!

turbid harbor
alpine sable
#

Alr thanks

#

Do you think i should make someone else double check

turbid harbor
#

our university teacher for maths said to switch around topics more, as its easy to be "on a roll" on one subject and just forget it if you dont repeatedly do them

alpine sable
#

Alr thanks

turbid harbor
#

:)) GL

turbid harbor
wise sigil
#

After the hint you should have sin(x) * y' + cos(x) * y = 2

turbid harbor
#

OOOOO i forgot sec(x)=1/cos(x)

#

thanks man 😄

wise sigil
#

With the equation in this form it's not too hard to realize that you should look at (sin(x) * y)'

turbid harbor
#

im gonna write some of these on post it notes around my house bc i reallly need to remember to llook for them more

wise sigil
#

You can also just divide by tan(x) and do the usual process to find an integrating factor for equations in the form y' + p(x)y = q(x) but you'll end up with the same result and it's more tedious

turbid harbor
#

it's bad that "y' + p(x)y = q(x)" confuses me 😂

#

got a feeling second year maths I will be coming in here crying a lot

#

:3

floral willow
#

@wary stream My current answer is $v = \sqrt{5x_0+v^2_0}$

ocean sealBOT
#

Willow

raw garnet
#

Could someone help me with Nonlinear Differential Equations and Stability? I don’t understand the bottom part of the solution. I know how to get the determinant and the trace but how do we know that it is the only critical point and that it is ass. stable spiral point?

velvet pelican
#

this one lies above det(A) = 1/4 (Tr(A))^2 and to the left of the y axis so it's a spiral sink

raw garnet
velvet pelican
#

no the plot plot of the soutions is different to the diagram i gave

#

you plotted on the x-y plane and the diagram is of the trace-determinant plane

raw garnet
#

Ohhh I see, my bad

velvet pelican
#

no worries

raw garnet
#

Yea I recognize the D T plane picture

#

I’ll look more into it now, thank you for the help

velvet pelican
#

welcome

alpine sable
#

Hey

#

Can someone help me find the gradient

#

Of i

#

Im confused

sterile gull
#

What is confusing you?

alpine sable
#

how to find the gradient

#

I got the y intercept

sterile gull
#

Do you know how to find slope for a given equation?

alpine sable
#

Yes

sterile gull
#

Yeah so gradient is just another term for slope

alpine sable
#

Ik

#

i dont know tbh at this point

gray isle
#

you said you knew

alpine sable
#

ik

#

y2-y1/x2-x1

gray isle
#

Do you know how to find slope for a given equation?
Yes

alpine sable
#

To find the gradient its y2-y1/x2-x1

gray isle
#

assuming you intended the appropriate parentheses,
that's the slope from two points, not an equation

sterile gull
#

Yeah this is when you are given the two points

gray isle
#

are you familiar with the slope-intercept form of an equation of a (non-vertical) straight line?

alpine sable
#

y = mx+c

#

Am I right?

#

To find the intercept

gray isle
#

y = mx+c
many other places use b instead of c

#

is the equation of a line in slope-intercept form

#

it is called the slope intercept form because the slope and the y-intercept can be read from that equation directly

alpine sable
#

well so that’s the equation correct?

jagged imp
#

Isn't the point of this question to introduce slope intercept form by having them find gradient from rise/run and relate that to the equation? part b asks you to find a pattern that is obviously meant to be discovering slope intercept form

#

i don't think they're supposed to be looking at the equation for a), just the plot of the line

alpine sable
gray isle
#

ig

alpine sable
#

Im doing 3D

#

Back to this

gray isle
#

in that case, choose two nice points on each line and apply the slope formula, and/or rise/run

alpine sable
#

Any points?

gray isle
#

what i initially mentioned applies to part b)

alpine sable
#

3, 3 and -5,-1

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Like that?

jagged imp
#

(3,3) and (-5,-1) but yes

alpine sable
#

Alr

#

So

#

-1-3/-5-3

gray isle
#

please use appropriate ()

alpine sable
#

My bad

#

-4/-8

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I might have messed up

#

Yeah I did

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Its -8/-4

jagged imp
#

yeah thats it

alpine sable
#

Yes im done

ancient bear
#

cool

stoic pier
#

hey i need help

#

how to do this ?

urban pollen
#

log 3.109 is equivalent to log 31.09 × 10^-1

#

then you use logarithm's multiplication rule (rule 1) to separate 31.09 and 10^-1

#

so you should get log 31.09 + log 10^-1, using the power law, bring down -1

#

then its 1.4926 - 1, so log 3.109 = 0.4926

stoic pier
#

oh uh thankyou vm

urban pollen
#

ah yea i saw the other channel HAHA sorry

stoic pier
#

never mind 🙂

manic glade
#

is it true to say that if A=2n, B=4n (n in N) and B subseteq C subseteq A
then |P(C)|=א?
and is it true to say that the power set of all infinite size subsets of an א_0 sized set is size א ?

cosmic geyser
#

i made a ski resort on a map, the ski resort is 200cm long on paper, I need a conversion for every 1 cm = x km on the map, i need it to be more than 80km in total

#

need help asap

stoic pier
#

iam here

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but

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idunno the ans lol

cosmic geyser
#

im trying to find out a website to figure it out for me but i cant :((

sterile gull
#

if you take 1 cm = 0.4 km then for 200 cm you'll have 200 * 0.4 = 80 km

#

I don't understand the more part tho

cosmic geyser
#

nvm

#

thx so much

alpine sable
cosmic geyser
plucky crow
#

is this channel taken?

alpine sable
#

lol ok then its wrong

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|P(C)| = c

manic glade
#

c meaning what here

alpine sable
#

continuum

manic glade
#

whats that

alpine sable
#

size of reals

manic glade
#

so.. א?

alpine sable
#

no

manic glade
#

the wiki page says its א

alpine sable
#

if by aleph you mean aleph_0

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aleph_0 is the size of naturals

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2^(aleph_0) is size of powerset of naturals

manic glade
#

א_1

alpine sable
#

which assuming CH is aleph_1 = continuum = size of reals

manic glade
#

so it is true then

alpine sable
#

no

#

|P(C)| > |C| for all sets C

manic glade
#

right

alpine sable
#

so |P(N)| > |N|

#

and |P(N)| = |R|= א_1 > |N| = א_0

manic glade
#

which = א

alpine sable
#

WHAT DO YOU MEAN BY ALEPH

manic glade
#

the size of c

alpine sable
#

aleph is not size of anything