#precalculus

1 messages Ā· Page 95 of 1

frosty folio
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Hey I have a question if anyone's free to help

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I'm trying to find the area of a quadrilateral with missing sides

hallow sluice
#

Yeah same here. Being self taught is fun but often gets rocky at times

gleaming walrus
civic moon
gleaming walrus
#

yeah that's what I mean

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this problem doesn't required you to know a lot about limits or derivatives or whatnot

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if you know the needed algebra theorems inside, you can solve it

civic moon
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Uhm have u heard of
$(x+h)^n = x^n + \sum\limits_{k=1}^{n} \binom{n}{k} x^{n-k} h^k$

obsidian monolithBOT
#

Scholar Of Mysteries

civic moon
#

@gleaming walrus

gleaming walrus
#

yes, I learned it to solve that problem

civic moon
#

Yea so what do u need help with? 😭

gleaming walrus
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I don't need help 😭

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I was talking in the discussion channel but I can't send images there

civic moon
#

Oh

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Alr mb!

median vapor
orchid urchin
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very usefukl

thorny remnant
tropic river
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Why is this incorrect?

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I used :

orchid urchin
tropic river
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I'm šŸ•Šļø

orchid urchin
# tropic river why?

I am not too sure what method you used but I divided the fraction, or the first term by x^2 on top and bottom and got (12x + 6 - 3/x^2)/(2 + 7/x^2) now the -3/x^2 and 7/x^2 as x approaches infinity reaches zero so those are negligble giving you (12x + 6)/2 which is just 6x + 3

tropic river
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12x3+6x2-3 = 3 . (2x-1) ( 2x^2+2x+1)

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and

tropic river
orchid urchin
tropic river
orchid urchin
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didn't see the 3

tropic river
#

k

tropic river
tropic river
#

2/2

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so

tropic river
#

x --> inf

orchid urchin
# tropic river x --> inf

your work makes sense but your taking the limit of not just a fraction but 3 things, namely the fraction, cube root and the 7x

tropic river
#

hm

orchid urchin
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all terms must be compared together before concluding anything

tropic river
#

?

orchid urchin
tropic river
#

why why

orchid urchin
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giving (6x + 3) + (x + 1) - 7x

tropic river
orchid urchin
#

that gives 7x + 4 - 7x which is just 4

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depending on how u do it if you get a 1/3x^2 lets say as x approaches infinity that fraction will be 0

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so it won't even matter you can just get rid of it

tropic river
orchid urchin
# tropic river why why

try factoring out a x^3 inside the original cube root, which does give x + cbrt(1 + 3/x + 1/x^3), and the idea here is that the cuberoot of (1 + 3/x + 1/x^3) approaches 1 + 1/3 * (3/x + 1/x^3), which after multiply out and taking the lim gives x + 1

orchid urchin
#

like the quadratic with the denominator

orchid urchin
# tropic river

oh I see you did do that, then you should have gotten x * (something small), which is x * cuberoot(1 + tiny) now you can use linearization which I did use to figure out what that cube root would end up being, but there is an algebraic way if u want to know

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its just painful

tropic river
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I have exam of calculus tomorrow

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i'm šŸ•Šļø

orchid urchin
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study up on linearization man

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or actually just those type of cube root limits

dark hollow
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is ap precalc worth or shld i jst take normal precalc

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i have the opportunity to take precalc in 10th and take ab/bc in 11th

round geyser
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How would we solve this

undone pumice
echo sinew
round geyser
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I remembered a^4-b^4

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That’s what I got

neat ledge
# round geyser

you can do the fourth power square root on both sides so you get 2x+1 = |3x+4| and that working out is quite easy

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i checked on my calculator and that should work

round geyser
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Yep

neat ledge
high sequoia
warm ibex
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Guys in a differential equation, What exactly is x and y?

y is a function of x right? so like y=y(x) or h(x) whatnot. And x in an differential equation is the variable, input for the function y.
and dy/dx is just the y derivative, y'(x).

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and in the image when we wrote g(y) this y in g(y) is the y in the dy/dx? so g(y) is a function which has an input of y=y(x)/h(x), and f(x) is just a function which has the input x, which is the same input y depends on?

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um sorry if i dont make sense at all.

spark anchor
round geyser
neat ledge
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it took me like 3 pages and 5 tries cause i tried stupid shit but i got it

round geyser
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I used nth root of(x^m) = x^m/n

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And get same base

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Then that cancels and left with 2x-1=x+1

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Subtract over to get x=2

neat ledge
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i simplified to (2^4x-2)^3=2^3x+3)^2 then just work it out to 2^12x-6=2^6x+6 and then you remove the 2 and simplify

round geyser
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Yea

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That works

rough leaf
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Is ts your TikTok account😭😭

pure sage
#

hey guys im new and i really need help with calculus...can anyone help me...

valid topaz
exotic barn
bronze geyser
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it has the same hieroglyphs on it

round geyser
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I go to all the mathematicians and place requests

round geyser
# rough leaf Is ts your TikTok account😭😭

Is this what u said ā€œif u want all solutions even complex then let LHS=a⁓,RHS=b⁓, so u get a⁓-b⁓=0, (a-b)(a+b)(a²+b²)=0, so a=b,a=-b and the last is just the quadratic so finding ex is trivialā€

sly narwhal
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Anyone know a place to find a good and quick explanation of why the properties of conics hold. All the hs curriculums just dumb it down and don’t explain crap and I’d rather not read 40 pages for this.

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I mean like all of the connections between all the ways to define conic sections and why cones connect to general 2nd degree equations. Figured out a lot on my own but I’m bound to miss some interesting things I’d rather not misss

round geyser
orchid urchin
# warm ibex Guys in a differential equation, What exactly is x and y? y is a function of x ...

x and y are nothing special, dy is just a little bit of y (lets say y is an hour a tiny bit of an hour would be 1 second for example), and dx is a little bit of x, so the ratio dy/dx is simply saying how much does y change when we change x (dx) by a little bit. Speaking precisely if you have x, then dx is the derivative of x, same with the y. In the image you show its a bit more complicated though because we have a function f, where x is the input and a function g where y is the input, and theres no derivate weird stuff happening there but we equate it to dy/dx. Depending on how far you are in calc you may realize you can seperate the variables and get (1/(g(y)) * dy = f(x)dx which you get by just algebraic manipulation, and the right side is the derivative of f(x) and the left side is the derivative of 1/g(y), or the reciprocal of g(y).

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dy/dx is read as "the derivative of y with respect to x"

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now you would want to integrate after rearranging

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you typically do differential equations after completing calc 2, or 3 as well

exotic barn
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<@&268886789983436800>

sly narwhal
round geyser
#

Ok

rough leaf
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Anf it looked familiar

round geyser
#

Okay

round geyser
#

Come pop up his live

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Really fun

sly narwhal
bronze geyser
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im first

distant kelp
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@gentle vault Hi

gentle vault
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Hi

viscid thistle
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Hii can someone help me with this? Im not sure if this is correct

uncut mulch
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Is incorrect

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why are you multiplying 3 to the 8x

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what is the derivative of 8x

viscid thistle
viscid thistle
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Im new to this stuff i just started learning today im learning by myself i dont go to school šŸ’”

viscid thistle
velvet wyvern
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,rccw

obsidian monolithBOT
uncut mulch
#

linearity and
power rule
check out stuff from organic chem tutor

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also use your space,
write stuff on new lines

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+- can also be simplfied down to -
making the final result
9x^2 - 8

velvet wyvern
viscid thistle
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ohhh okay i see thank you!!

gentle vault
tribal wind
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any good vid for continuity and differenciability,
and tricks for integration, highschool level to solve multiple choice questions?

urban kernel
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Far easier.

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Also, continuity is not that hard imo.
A function is continuous if for all c in its domain, lim_{x->c} f(x) = f(c).

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A function is differentiable at a point if it is continuous at it, and also smooth.
Extend it to all points for a differentiable function.

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The smoothness is given by the limit of the difference quotinet.

rugged sleet
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I see you mention 'smooth' but I think that this definition is a bit dangeroous to operate with. Would be better to prove that a function is differentiable at a certain point and hence continuous at it. Smoothness is just a vague term, in several cases you can't declare a curve to be smooth at certain point without checking if it is differentiable at it.

urban kernel
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I see.

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I will take better care.

tribal wind
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ohhh thank youuu @urban kernel @rugged sleet šŸ›šŸ›šŸ›

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do u have any videos? a short one, just for explanation works

urban kernel
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Remember, i am not recommending this for rigour.

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It's for intuitive understanding.

orchid cedar
orchid cedar
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like when your input approaches a value, the function's output also reflects that

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its output gets closer to the output of f(that value)?/

urban kernel
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Yeah..., you can say that

orchid cedar
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why though?

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why does continuity depend on that?/

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like isn't it obvious?

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does every function not support that?

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why?

rugged sleet
orchid cedar
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ahh ok

rugged sleet
orchid cedar
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but if it breaks, there will be atleast one value that makes the function undefined

rugged sleet
#

Check this example:
f(x) = x^2 if x>=2 and f(x)=2x-1 if x<2

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To determine if f is continuous at x=2, you will have to check if lim x->2 f(x) = f(2)

orchid cedar
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hmm

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ok

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what about the second function

rugged sleet
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So, for the provided function, can you comment on its continuity at x=2

orchid cedar
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oh, nvm

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ok

orchid cedar
rugged sleet
orchid cedar
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yea yeah srry

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hmm ok

rugged sleet
orchid cedar
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uhh....... about that

orchid cedar
rugged sleet
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if lim f(x) exists as x->c then this applies that its right and left hand limit exist and are equal.

orchid cedar
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hmm

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wait, how do u know which direction to approach fro

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m

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do u do both

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what if the limit exists on one side

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what would that entail.

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it would be dis-continuos right

velvet wyvern
orchid cedar
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like x + dx or x- dx

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or is that not how that works?

velvet wyvern
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you take both limits

orchid cedar
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ok

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but : "You must take both limits"?

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otherwise, it would be incomplete

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right?

velvet wyvern
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elaborate

orchid cedar
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i digress

velvet wyvern
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?

orchid cedar
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what i mean is that, if we take the limit from one side, that does not like fully define the function cuz it may be dis-continuos from the other side

velvet wyvern
orchid cedar
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yes, so one must approach from both sides, before declaring that its continuous

velvet wyvern
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right

orchid cedar
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thanks!

hardy venture
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$\sin^2(x)+\tan^2(x)=\cos^2(x)-1$

obsidian monolithBOT
#

YeetusDeletus5

thorny ingot
round geyser
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x=?

valid topaz
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newton's method?

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i don't rly see a nice way to do this

nimble wolf
round geyser
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I get P/Q is 1,1/2,1/4,3,3/2,3/4

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6x2=12 possible solutions

valid topaz
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wait ||3|| is a solu

nimble wolf
round geyser
#

x=3,-1,-1/2

valid topaz
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hmmmmm

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oh i was being dumb

round geyser
#

Two repeated roots; -1 and -1/2

nimble wolf
round geyser
#

According to desmos

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When I did rtt, my teacher let us use desmos even on quizzes and tests

foggy rampart
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There is a freshman in my pre-cal class

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I am so jealous of him

heavy ridge
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im new here what do i do

hushed sphinx
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That depends on what you want to achieve.

surreal iron
undone pumice
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ik a few other kids in my school doing it (like... 3, 4 that i know of)

foggy rampart
undone pumice
foggy rampart
#

No one at my school likes math like i do

undone pumice
round geyser
undone pumice
round geyser
#

Yep

novel lantern
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Where do I go from here?

exotic barn
#

,rccw

obsidian monolithBOT
exotic barn
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and then apply on both sides the exp func

novel lantern
#

Went ahead and did that @exotic barn still kinda rough on this

exotic barn
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Apply e^x on both sides

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bryh

obsidian monolithBOT
novel lantern
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Why would applying e^x to both sides work in this case?

exotic barn
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The roots of the quadratic are 0 and 10 and since the leading coeffcient is positive, it's open upwards, so within the roots it would be negative

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because e^x is the inverse of ln (I am assuming log means here with base e)

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but you can take any base

novel lantern
#

Right… Knew that just need to make cheat sheets.

exotic barn
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Np!

hallow flicker
uncut mulch
#

exponential function

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e^

hallow flicker
#

oh

orchid urchin
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specifically the base of the log

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and when u write a straight bar is that abs value?

orchid urchin
# novel lantern

ah nvm this was yesterday, just take away that e^x is specifically the inverse of ln(x), NOT log, but in your problem assuming the straight bars are abs symbols then you can just change log(24) and change it to log(24/|x|) giving you:

log(|x - 10|) = log(24/|x|)
And since there is no notation provided for the base it is assumed to be 10, with that being said they have the same base here so you can remove the logs giving you |x - 10| = 24/|x| where x cannot be 0 (otherwise division by zero).
Solve to get:
|x(x-10)| = 24
And split into cases:
x(x-10) = 24
x(x-10) = -24
You should know what to do from there

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Also for the step where you just remove the logs, note that a log is injective making it one to one, and if you want more intuitive reasoning think of the situation where you raise a constant b to the power of log_{b}(x), which is just x, and instead of applying "e^x" you would just apply the base of the log to get rid of them.

orchid urchin
obsidian slate
#

easy question to try removed

gentle vault
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um

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Idk tho

obsidian slate
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oh it wasnt on my channel list for some reason

round geyser
echo sinew
round geyser
echo sinew
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I guess so

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But what's the issue with this exercise? Which part are you having trouble with?

dry verge
#

Did Khan Academy mess up?

raw hill
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where did x go pandahmm

dry verge
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Oh wait, I realized that they talked about the co-vertices and not the vertices.

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The answer isn't an imaginary number, whoops.

round geyser
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The first method is synthetic divison

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I think

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Then I got R(x)=6

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Will it be (x+1)(x-4)+6

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Since we know (x+1)=0 then
0(x-4)+6

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Then it’s 6

uncut mulch
#

what does this have to your previous question

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also this isn't what the question is asking for

round geyser
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If it that I have to solve the first requirement

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To get the second

uncut mulch
#

but what does that have to do with the f(x+1) = x^2 - 3x + 2 image you posted

round geyser
#

To the first

uncut mulch
#

they responded
they were waiting for you to say which part you had trouble with

round geyser
#

It was the reasoning

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The wordings are confusing to me

uncut mulch
#

did you do part i)

round geyser
#

I thought I have to do a then b/i

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a is easy

uncut mulch
#

i mean b i),
there's only one i) there so i ditched the a

round geyser
#

It’s subtracting the ā€œlog_2 x^2

round geyser
uncut mulch
#

wdym

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you said a) was easy, so i'm assuming you did that already

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b) i) is a continuation of that

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solving the equation you just got

round geyser
#

Okay

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First one was condensing

round geyser
#

That’s what I got

uncut mulch
#

continue solving, you're not done with that yet

#

you've only factorised,
haven't explicitly stated the roots yet

round geyser
#

We get x=-5/3 and 6

round geyser
#

log (-x)= undefined

uncut mulch
#

poor wording

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log(negative value) is undefined.

round geyser
#

When I plugged in -5/3

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I get 2 + 2 log (-5/3)

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On RHS

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Which is undefined

uncut mulch
#

yes

round geyser
#

Like this

round geyser
#

I assume x=6 works

uncut mulch
#

didn't really need to eval the whole thing,

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just starting domain and/or log(-5/3) is undefined is sufficient

round geyser
#

Guess what 6 works

uncut mulch
#

you've also dropped the 2 in front of the log on the right side when plugging your values in

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and the way you're evaluating when x=-5/3 is also bad

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because you're essentially doing algebra that ignores the restriction that disqualifies it from being a solution

round geyser
#

Okay

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What would the domain be

uncut mulch
#

intersection of all arguments of the logs being greater than 0

round geyser
#

Bc when I saw the graph

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They touch at (1,0)

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Do I write x>0

uncut mulch
#

x>0 would be the domain, yes

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the way you're evaulating it

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,w log(2,(-5/3+3)(-5/3+10)) = 2 + log(2,(-5/3)^2)

uncut mulch
#

would actually be true

orchid urchin
#

because the origional equation on the RHS is not squared

uncut mulch
#

yes..

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that's the point i'm making

orchid urchin
#

oh okay

orchid urchin
uncut mulch
#

yes

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first letter is the greek rho

orchid urchin
#

thats cool

young spire
#

@tired garden
hello, can i ask you a question?

round geyser
#

Okay

#

Is there a formula that has that Greek letter that measures density

echo sinew
#

Ī»: line density
σ: surface density
ρ: volumic density

These are usually used in physics/engineering

#

I remember them appearing on electrostatics, and also a little bit in mechanics

round geyser
#

p=mv

echo sinew
#

Huh, that's not a density

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That's linear momentum

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(Sometimes I've found it called q)

echo sinew
round geyser
#

With has volume

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ρ= something/volume

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You know what I mean

echo sinew
#

Now yes šŸ˜…

round geyser
#

What is it

echo sinew
#

ρ = mass/volume

round geyser
#

Yess

echo sinew
#

But often this is simply called d, not ρ
(at least in my country)

round geyser
#

g/cm^3

round geyser
round geyser
echo sinew
echo sinew
round geyser
#

Distance = speed x time

echo sinew
#

Oh yeah you've changed it my bad

#

That's only for uniform rectilinear motion though

round geyser
#

Is this right

echo sinew
#

It's simply "whatever unit for mass" / "whatever unit for volume"

round geyser
#

Okay

echo sinew
#

The international systems uses kg/m³, but often you can encounter g/cm³, g/L, mg/mL and so on and so forth

round geyser
#

Okay

echo sinew
#

But this is physics, not calculus

round geyser
#

We can convert them easily if I remeber

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Okay

echo sinew
round geyser
#

Okay

round geyser
#

Ik cent is

echo sinew
#

"centi" means a hundredth (aka 1/100 or 0.01)

round geyser
#

Ok

true geode
#

jeez, vary your responses at least

#

you come across as a redstone repeater, just outputting the same thing over and over again

#

...yes I know that's not technically what they do just deal with it

winged nexus
#

he seems interactive enough to me

dire aspen
#

okay

round geyser
#

Who

stark solstice
#

fk precalc

amber narwhal
orchid urchin
orchid urchin
#

any1 know the most elegant part of precalc?

round geyser
#

What

echo sinew
#

Indeed, how do you measure elegance? šŸ˜…

smoky schooner
#

Guys i made fun notes of calc like the idea of it in a fun way does anyone want to have a grasp

round geyser
#

Is bearing same as angles

uncut mulch
#

Not quite

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bearings use angles to describe direction

cerulean phoenix
#

Can somebody explain that question marked line only?

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ignore the language cuz there is no english translation for me

potent slate
#

At x = 5 (upper limit) it will be
(5sqrt(25 - 25))/2 + 25/2 sin^(-1) (1) = 0 + 25/2 sin^(-1) (1)

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At x = 3 (lower limit) it will be (3sqrt(25 - 9))/2 + 25/2 sin^(-1) (3/5)

atomic violet
#

ive done too many area under the curve to forget ab this 😭 thermo fluids is killing mee

i know of exponent rules like 1/x becomes x^-1

however how do i integrate that exactly? you add 1 to the power and divide by the new power

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am i missing something there

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you cant divide by zero

smoky schooner
cerulean phoenix
willow wraith
#

It’s ln|x|

thorny lily
#

hello guys, I’m new here and just starting out with calculus. Could anyone suggest some good resources to help me get started?

willow wraith
#

looking into conceptual problems first

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usually starting with physics actually

thorny lily
#

which physics problems do you think are best for beginners to grasp the core concepts???

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any resources you’d suggest for learning?/

willow wraith
#

classical mechanics problems will may help you learn WAY more why calculus is needed and you’ll start to see relationships that kind of usher in calculus

valid topaz
#

<@&268886789983436800>

proven pagoda
#

i get into this chat and i feel like "dang, ap precalculus failed me šŸ’”"

hushed sphinx
#

There are often people who for some reason or another try to talk about calculus questions here instead of in #calculus.

#

So don't assume everything being spoken about here is something a precalculus class should have taught you.

proven pagoda
#

that channel isn't even showing up on my server channel list, i guess I didn't dd all of them lol

proven pagoda
hushed sphinx
proven pagoda
#

yes yes i did

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lol i thought i did that already

hushed sphinx
proven pagoda
#

yeah the exp and my curriculum never used abs value

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and the arrow is that just like simplification or

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i can see the math it's just stuff ive never approached i guess

potent slate
#

The arrow is an implication arrow
A ⇒ B (B follows from A, or A implies B)

potent slate
proven pagoda
#

like do i know what absolute value is? yes, i've just never used it graphically and i haven't done any solving with it since 9th grade lol

potent slate
#

As you can see, the output for a modulus is always non-negative

proven pagoda
#

so can an absolute value's function never have a y value of -a?

proven pagoda
#

alright

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what cabn transformations look like

fossil kindle
#

when is |x| even used

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alg 2?

proven pagoda
#

and i think i used it in geometry a little bit in real world problems?

fossil kindle
#

they introduce it but i dont think they actually do anything w/ it

proven pagoda
#

idrk i don't remember lol

fossil kindle
#

besides distance but thats not really using the parent function tbh

proven pagoda
#

all it really is is just the distance from 0 so

potent slate
proven pagoda
#

and then b(x-h) i'm guessing is horizontal compression or stretch?

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or slope

#

lol

potent slate
proven pagoda
orchid urchin
novel lantern
#

Getting stuck again. Simple algebra failing me

#

Nvm forgot can factor it

viscid thistle
#

Istg if I have to do this STUPID axes rotation by angle transformation again in calc I will die

#

Actual nightmare

raw hill
#

Me when eigenvalues of $\begin{bmatrix} a & b/2 \ b/2 & c \end{bmatrix}$

obsidian monolithBOT
#

Civil Service Pigeon

viscid thistle
#

25 minutes of my life down the drain

orchid urchin
#

what u typin

loud fossil
#

me?

orchid urchin
#

@loud fossil

loud fossil
#

-.-

orchid urchin
#

I mean getting help doesn't mean your bad at math

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just means your improving

smoky schooner
#

I hope this will help,p

#

So let me wrap up everything I said. So basically the derivative and the limit is is like something that is widely misunderstood upon others. For example, the derivative is mostly known as the accurate change like the accurate change that's not like like the slope. But actually the derivative is how much the velocity or the thing we're measuring changes as we as it approaches and this approaches zero meaning it's more than the accurate change. It's something related to the physics behind of the thing and not only the numbers. Like it's not just the slope it's literally the physics everything behind it. For example, so we have a car. So the car is basically transferring energy from chemical to mechanical to kinetic. The chemical part is when the car is not even moving is when the car is literally at zero zero constant velocity or the unit we're measuring it in and as it moves and this approaches zero when this mechanical and chemical energy turns into kinetic it increases and gets away from the zero. But as the friction of the ground acts as a external nerving uh force that's like how Newton Law said that any force second law actually that any force acted by another force is the only way the force can change. It decreases and makes it approach zero. So when we solve something like 3x^2 the derivative is basically when

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we manage the power we're basically measuring how much it approaches zero and then when we are multiplying the constant it's basically how much like it's getting away of zero. So it's basically widely just connected to physics more than just numbers and abstract proofs. It's basically the way we should look at look in it when we actually solving real life problems instead of just looking for how much is the rate of change. We should look of how much does the thing change as it approaches and this approaches zero. And this gives us more accurate and more reliable answer that can be used for any operation then if we're using it for only the slope we're basically just like we're basically just like um finding an answer for the temporary state. And when we say it's an accurate estimation we're just saying an accurate estimation for for example a two points and then that we combine but it's actually a way to solve this problem forever like without actually having to measure every single part of the of the graph. So the misconception is that if the thing that we actually believe is that derivatives that means we need to actually measure every single small part while we're only measuring how much the thing changes as it approaches and this approaches zero. And when we zoom in into something we're just seeing the little slope of the thing instead of seeing how much is the change over certain time for a more reliable answer we use the derivative that is actually the real versus the misconception which is just a dumb idea of what we see that's only used for hard like thinking cuz if what it was actually true we'd sit years trying to find the derivative. And basically the the thing changes as the the the the certain type of graph changes is what changes the way and method we use for example power rule, chain rule, etc. And this gives us an accurate estimation that helps us understand everything very well. I hope you enjoyed what I said.

jagged lintel
#

why is your room so orange

fossil kindle
crimson onyx
novel lantern
willow wraith
#

you’re overcomplicating it a lot

#

In physics for position functions your input is usually a time

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so the derivative of that position function throughout a time interval would just be dp/dt

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meters / second

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which is just velocity

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Velocity with respect to a time is acceleration

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and instantaneous slope is just the slope over an extremely small interval as the length of that interval approaches a finitely small number

#

So just this

smoky schooner
#

What ur saying is technically kinda the same as what i said

smoky schooner
#

But am saying

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How do we find this conctusie sle

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Slope(

smoky schooner
willow wraith
#

<@&268886789983436800>

dry verge
#

Did I do something wrong here?

rough leaf
#

Qait

#

It’s gonna be 13sqrt2/2 - 13sqrt2/2 i

crimson onyx
dry verge
#

Thank you so much! That was much simpler than I thought it was going to be.

viscid thistle
#

DONE WITH CONICS YAYAYYAYAY I HOPE I NEVER SEE THESE EVER AGAIN OMLLLL time for sequences and series hope this ain't harderšŸ˜›

undone pumice
#

gulp wow

viscid thistle
#

once I do s&s I will be DONE with precalcšŸŽ‰

undone pumice
#

what is s&s?

viscid thistle
undone pumice
#

ohh

viscid thistle
#

I acronymed it cuz I said it msg before

undone pumice
#

ah

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oops i can't read fah

viscid thistle
#

how hard would you guys say sequences and series is compared to conics and paras

orchid urchin
orchid urchin
#

although if your not self study it will probably be around the same difficulty

viscid thistle
#

oh great 😭

#

im self studying so im cooked lol

orchid urchin
#

im self study so I had to learn it in so much depth, and rederive where all the formulas come from and develop new techniques to invent new ones

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because you have to learn all the basics which go by fast, for the single sum, and nail the notation down with practice and the rules for it and why they work.

#

and then move onto double sums

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then triple

#

until you get the pattern and you can do quadruple on your own

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thats how I did it atleast

#

and then taking a sequence of numbers and thinking about it as a function and finding first differences, second, and third, and so on

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and then finding the degree of the polynomial based off of that

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for f(x)

#

and rederiving the equation using the form Ax^3 + Bx^2 + Cx + D for example

#

and you would do so by setting up a system of equations and setting the polynomial to the sum of the first term, first two terms, first three terms, and first four

#

so @viscid thistle it can get kinda crazy if you mean to go deep

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definitely worth it though because now I look at it and be like, oh this stuff is easy

#

as when I first saw it I couldnt do it at all

viscid thistle
#

alr, wish me luck then😭 so far I litteraly just started 2 minutes ago so

#

imma stuydy for 4 hours straight

orchid urchin
# viscid thistle imma stuydy for 4 hours straight

the start should be rather easy, the formulas for a linear sequence are just simple and the sum is simple as well and creative depending on how you want to intepret it if you do research that, same for geometric, once u get into sigma notation and that type of stuff though then you will be able to invent those types of formulas

#

the weirdest thing I do till this day is factor out a sigma

orchid urchin
#

since the sigma literally just means add and its all linear u can just do that

viscid thistle
#

so if the sum of x's was 10 then would it be a(10) +b(10) = (a+b)(10)?

orchid urchin
#

because if u set 10 to u so 10 = u you will have au + bu = u(a+b) @viscid thistle

#

thats one way u can think about it

viscid thistle
#

nice, thank you

viscid thistle
#

@orchid urchin yo arithmetic sequences lowk rlly fun

#

nvm just sequences

#

im aboutta do arithmetic

viscid thistle
#

let me try it

#

im not sure if I got this right at all since I litteraly had no idea what was going on so I made up a thing on how to do it lol

#

51?

raw hill
obsidian monolithBOT
viscid thistle
#

whooop

raw hill
#

You seem to be off by $6=1+2+3$, so maybe recheck somewhere there

obsidian monolithBOT
#

Civil Service Pigeon

orchid urchin
#

which is lowk easy

#

and calculus too if u can do that

orchid urchin
#

i personally would recommend not using the geoemetric series formula

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and learn about telescoping series to solve that

smoky schooner
gentle vault
#

$pi$

obsidian monolithBOT
#

šŸ—£

gentle vault
#

Uh idk

crimson onyx
#

Wat

fossil kindle
silver robin
#

Can someone help me with understanding the use of tangents and normals in conics?

shell current
#

The ones done were in class, didnt get it someone mind explaining 7, 8, 10, 12 my dms are open anytime.

haughty crown
shell current
shell current
undone pumice
shell current
#

ive noticed that, i was never great at algebra bcs i never focused in class lol

haughty crown
#

I sent you a message R

undone pumice
young spire
# tired garden sup

hope you're doing well, here is the question:
i struggle to understand the change of base rule of logarithms. even though i made a proof for it myself. i understand the proofs but they don't really explain anything. they just show you why the rules work algebraically but i want to know the logic behind the rule.
i don't understand that why you get a completely different base when you divide two logs, with the same base.
i asked the same question when I tried to make sense of adding up rule. I asked the question of why you multiply the input values when you add up logarithms with the same base? How does this actually work when all you're doing is summing exponents up? and why doesn't this work when you add up logs with the different bases? I was desperate by answers, so i asked that question to ChatGPT and it told me this:
"You are trying to mix two different counting systems into one system."
that made kinda sense but my gut says that it didn't explain anything mathematically, thus this is not really reliable or understandable.
can you tell me the logic of base of logarithms?

#

there are literally too many rules in logarithms and it feels kind of frustrating to make sense of all them.
i could just use them as tools which will save me a lot of time and would be actually smart since I need to pass the universty entrance exam but i have a lots of time ahead of me plus that's not really how i study.

hushed sphinx
#

It's a bit hard to know what will help when you already have a proof and that doesn't convince your gut ...

#

But ... suppose the only way you know to calculate powers is b^y = exp(yĀ·ln(b)).
Then, instead of looking for log_b(x) as a solution to b^y = x, you're solving x = exp(yĀ·ln(b)) which is the same as ln(x) = yĀ·ln(b).

young spire
#

would you like to learn my proof

hushed sphinx
#

Another way to look at it would be to say: Logarithm functions are just arbitrary multiples of ln -- after all, these all satisfy f(xy) = f(x)+f(y), by linearity.
And we define the "base" of one of these functions to mean the input that happens to map to 1.

tired garden
#

also, are you comfortable with exponent rules? because if you are, log rules are really not far behind

lunar pumice
lunar pumice
#

ok so as tropo said, try to turn your log rules to use exponents

#

like, what does log(xy) = log x + log y mean?
what does that look like if you had to write it with exponents instead

young spire
lunar pumice
#

a^??? = xy
a^? = x
a^? = y
a^??? = xy = a^? * a^? =
i know this is far from valid math but you would think about that rule like this

#

the ? is why logs are helpful

#

anyways with exponent rules you would have a^(? + ?) = a^??? = xy
so ??? = ? + ?

#

thats why a log xy = log x + log y

young spire
#

yeah, actually that's why these rules are called as "the properties of logarithms" because you can prove them by the very own definition of logarithm and exponent's basic properties.

#

loga(x)=y <=> a to the power y = x
i assume that all the properties are basically the interpretation of this definition

lunar pumice
#

well yeah log rules are just what happens when you use exponent rules

#

and write them with logs

tired garden
#

just checking, are you saying that angel's explanation is one you already know but doesn't satisfy you?

hushed sphinx
# young spire

Yeah, that goes through so many steps that it's understandable if it doesn't produce much intuition. I would instead start just with the definition of log_b(a) try to derive the fraction at the end of the calculation:

log_b(a) is the solution to b^x = a.
But b is c^(log_c(b)), so this is the same as c^(log_c(b)Ā·x) = a.
Now take log_c on both sides again, giving log_c(b)Ā·x = log_c(a).
And now you only need to divide through by log_c(b) to isolate x.

lapis shuttle
#

sorry for intruding guys but uh... are ALL of these answer choices wrong or am i just not understanding

lunar pumice
#

ok i don't really understand what you are asking

#

you know log rules exist because they are just exponent rules written in a different way and you ask why that is?

tired garden
lapis shuttle
#

ok thank you

#

I thought i was tweaking

tired garden
#

is that your ask?

young spire
tired garden
#

you mean like the change of base stuff?

#

here's how i like to think about it:

#

but before i proceed, let me clarify some vocabulary to be rigorous

#

if we say "three fives make fifteen", the "make" here implies that we are adding the 5's together

#

i am going to use the same language, but i will use multiplication instead, since we are working with exponents and logs

#

so in this case it would be "three 5's make 125"

#

make sure to always think about multiplication as our "building action", not addition

#

when we say log_b c = n (aka b^n = c), we are essentially saying that an "n number of b's make c"

#

does this make sense so far?

#

to "visualize" it you can think of the b's as objects, grouped into boxes, with n of them in each box, and c is the value of the entire box

#

@young spire ping me if you're comfortable with this visualization and ill proceed

young spire
tired garden
#

just checking

#

ok so

#

lets say we have as in your proof log_c a and log_c b

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picture a as a giant box, picture b as a small jar

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log_c a is how many objects fill the box

log_c b is how many objects fill the jar

#

so log_c a / log_c b is basically the number of objects in the box, divided by the number of objects in the jar

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what is log_b a? the number of jars that go into the box

young spire
#

i didn't quite grasp the situation

#

chatgpt told me something similar to this, refering to the ratio

tired garden
#

what in particular do you struggle with? can you point to something more specific?

young spire
#

the thing that i struggle with is that how do we get to the base b

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like, why does this ratio lead us to log_b(a)

lunar pumice
#

maybe write it as exponents

tired garden
#

lets try a specific example

#

so log_2 512 / log_2 8

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imagine 2 as a ball

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i can fit 9 balls into a box, which i will use to represent 512, as 2^9 = 512

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similarly, i can fit 3 balls into a jar, so the jar is 8

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log_2 512 is how many balls fit in the box

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log_2 8 is how many balls fit in the jar

#

so what is log_8 512?

#

that would be the number of jars that fit in the box

#

does this help?

young spire
#

when you divide logs, dont you divide the exponents

#

i dont understand how the base just come in to the solution, i guess the base matters only if you try to write it as another log

tired garden
#

do you at least follow my intuition

#

perhaps we can figure out how to explain away the confusion through that example

young spire
#

the problem is here

tired garden
#

well, we said log_8 512

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8 is the jar

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512 is the box

#

since 8 x 8 x 8 = 512, 3 jars fit into the box

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and that is log_8 512

#

so log_8 512, in our example, can be visualized as the number of jars that fit in the box

young spire
#

why do we find how many jars would fit in the box

tired garden
#

because the entire point of this was to help with visualizing the concept

#

you dont have to do this at all

young spire
#

no no, like

#

loga(x)/loga(y)=log?(???)

#

when i first saw the rule, i asked to myself that if i was finding this rule, what would i do to divide two logs? as it turned out, i was struggling to determine the base.
its easy to prove the rule when the base is determined and all you need to explain is why ... is equal to ...

tired garden
#

so we can either pretend we know the left side and figure out the right side or vice versa, which way do you wanna approach first?

young spire
#

we should try to find the left side (base) and pretend to know the right side (input)

tired garden
#

ok

#

so let's pretend that, once again, 8 represents the jar, and 512 represents the box

#

so log_8 512 represents the number of jars that fit in the box, which we know is 3

#

but let's say we don't measure this directly, we don't just shove the jars into the box and count

#

let's say we have to use some kind of measure, like volume

#

we say, for instance, the jar is 1 liter, the box is 3 liters, or something like that

#

except instead of measuring in liters, we measure in balls

#

what is a ball? doesn't matter, literally any amount

#

so hypothetically, if we set the ball to be 2, as in our previous example

hushed sphinx
# young spire i dont understand how the base just come in to the solution, i guess the base ma...

I wonder if some of the problem might be that you expect the rule to work like "we must always rewrite this to that when we're doing calculations". That wouldn't be a helpful way to look at it; it is more "these two different calculations always yield the same result" -- a plain fact that you can then do with what you want. It can sometimes be useful to replace one with the other or vice versa when that happens to make something you want to do simpler.

tired garden
#

we can find log_8 512 by first measuring the amount of balls that fit in a jar, then the number of balls that fit in a box, and this can be a proxy to find the amount of jars that fit into the box without directly measuring jars inside the box

#

the ball could be any other value and this would still work

#

you can try this with the ball being sqrt2

#

and that's why the general base c just appears, and can be anything

hybrid leaf
#

Does anyone have AP Precalc exam prep materials that are either legit or leaked? I need resources for final exam and especially help for FRQ#2 part Bii and C

hybrid leaf
potent slate
#

Well, do as much as you can

haughty crown
#

Try to find a video on YouTube explaining it, instead of just doing it @hybrid leaf

potent slate
#

I can help you out for Bii. What did you get for Bi??

#

Your answer in Bi is your rate of change per month (slope) for the equation you have to compose in Bii

#

By what is given, 25 is your intercept (at t = 0) soooo you can make up a slope-intercept form equation and solve for x = 1,5

#

sorry, I meant to say t, not x lol

undone pumice
#

cus frq 1 and 2 r both calc so i can do that

hybrid leaf
hybrid leaf
#

For example when it says determine the domain, technically the question doesn't say you have to find the domain but i believe that you are expected to find it

hybrid leaf
potent slate
#

Oh 😭

hybrid leaf
#

mb

potent slate
#

@hybrid leaf D is a quadratic that opens down and increases on [0; 4]. A_t is a secant line to the quadratic

#

So concluding from that, why is A_t always less than D(t)?

#

Example of a concave-down quadratic and a secant line

potent slate
hybrid leaf
#

Yeah... I can do the explanation part but I guess my main issue is not not kowing how to solve the problem... it's writing what they want

#

should I just write everything I know in hopes that one of those is what they want

potent slate
#

Well, if you know the explanation, write it down??

#

I basically gave you the entire answer

hybrid leaf
#

that the function has a maximum so the domain is from 0 to where that maximum is?

potent slate
#

Exactly

hybrid leaf
#

right. But now should I do the work to acc find the domain

#

or is that enough

potent slate
#

In part A, you found D(t)

#

Just use maximum = -b/2a

potent slate
#

Anyway, happy to help)

#

If you have any more questions, feel free to reach out here

zenith sigil
#

Me and @crimson wraith need help with math

tender questBOT
# zenith sigil Me and <@728313540959535225> need help with math

Asking the actual question right away is more likely to get responses.

Asking "Can I ask...?" or "Does anyone know about...?" doesn't give people enough information to decide whether they can help, and answering can feel like a promise to help with the actual question, which they might find themselves unable to.

zenith sigil
#

Uh

potent slate
echo sinew
round geyser
#

Why do we use this

#

For finding distance of one point

round geyser
subtle flicker
floral gorge
# round geyser

do Eqn 1 Ć· Eqn 2
(x^2y^2)/(xy^2) = 36/18
x = 2

sub x = 2 in Eqn 2
2y^2 = 18
y^2 = 9
y = +- 3

therefore x/y is +- 2/3

floral gorge
#

you can prove it with vector geometry later on

round geyser
round geyser
#

h=12, k=34

floral gorge
round geyser
#

The long way is

#

Make a slope formula

#

And use the distance formula with sqrt((sum of x)^2)+(sum of y)^2)

round geyser
hushed sphinx
#

Presumably it is a parabola with vertical axis (without assuming that there isn't a unique solution), so plug those three points into y=ax²+bx+c, giving you three equations in a, b, and c that you can solve.

#

You can also wing it less systematically by writing down a function for the line through (8,0) and (14,18) and then adding an appropriate multiple of (x-8)(x-14) to make it pass through (12,16). That's a simpler calculation but perhaps more conceptually confusing.

bold crag
#

It's just like by quadratic general equation y=ax^2+bx+c

round geyser
#

It’s y=-ax²+bx+c

hushed sphinx
#

<@&268886789983436800> MrBeast

round geyser
#

I also noticed (8,0) is on x-axis

hushed sphinx
#

You can write it in that form too.

round geyser
#

When I graphed it

#

(14,18) is the vertex

#

So then it’s y=-(1/2)(x-14)^2+18

round geyser
#

Or y=-(1/2)(x-8)(x-20)

#

Even I can use mean value theorem on (12,16) and (14,18)

round geyser
potent slate
# round geyser

Case 1: x = x - 1 => 0 = -1. Doesn’t work
Case 2: x = -x + 1 => x = 1/2 (only real solution)

hushed sphinx
#

1/2.
1/2 ± i/2
1/2 ± (1+sqrt2)i/2

brisk raft
obsidian monolithBOT
round geyser
#

Just got that

brisk raft
#

use the complex sqrt perhaps

#

$$\left(\frac{x}{x-1}\right)^8 = 1$$

obsidian monolithBOT
round geyser
#

Set that to u

#

u^8=1

hushed sphinx
#

Wolfram writes the imaginary parts weirdly, but sqrt(3+2sqrt(2))/2 is the same as (1+sqrt(2))/2.

round geyser
#

Okay

#

Thanks

brisk raft
#

then immediately you have that $x = \left{ \frac{\zeta}{1 - \zeta} \right}$ with $\zeta = \exp(2\pi i k / 8)$ for each $k = 0, 1, 2, 3, 4, 5, 6, 7$

obsidian monolithBOT
hushed sphinx
#

And there's a pair of solutions I missed with imaginary part ±(1-sqrt2)i/2, which I really should have exepected -- they correspond to an 8-pointed star with edge length 1 rather than a regular octagon with that edge length.

brisk raft
#

exclude 0

#

cuz 1-1=0 so x/1-x =undef

#

šŸ™ƒ

round geyser
#

Btw

#

x≠1 is the domain

brisk raft
hushed sphinx
brisk raft
#

very nice

hushed sphinx
#

So I was looking for regular polygons with number of sides dividing 8, and side length 1, where one of the sides could be the line between x and x-1.

round geyser
#

x^5-1 has complex solutions that is with radians

brisk raft
#

yes you can use roots of unity

#

$x^5 - 1 = 0$ has solutions $x = {\exp(2 \pi i k / 5)}_{k = 0, 1, 2, 3, 4}$

obsidian monolithBOT
brisk raft
#

,w x^5 = 1

obsidian monolithBOT
brisk raft
#

did i mess up somewhere thonk

#

oh well

#

i will ping Moderatrosand you will be banned.

#

LMFAO did he get banned 😭

west peak
brisk raft
#

idk why wolfram alpha decided to omit a solution

valid topaz
#

||square (1+i) first||

hushed sphinx
#

Add then square it once more.

orchid urchin
#

for all terms except first and last

#

and you find every part that is imaginary

round geyser
#

I get [(1+i)^2]^14

#

(1+i)^2=2i

orchid urchin
idle field
#

use the polar form

round geyser
#

Is that right

#

2^14 * i^14

#

According to this

#

We use -1

orchid urchin
#

this is propaganda

round geyser
orchid urchin
#

chinese

round geyser
#

It’s -16,384+0i

#

So it’s 0

#

I like solving this

#

I get log_2^a (log_2^b (2^1000)) = 1

orchid urchin
round geyser
#

Then

#

Now it’s (2^a)^1

#

Or log_2^b (2^1000) = (2^a)^1

round geyser
orchid urchin
round geyser
#

I thought it’s 1000*[log_2^b^2]=2^a

orchid urchin
# round geyser I thought it’s 1000*[log_2^b^2]=2^a

well you can keep going in layers, like the first layer which is log 2a and all that stuff = 2^0 = 1, and then the second layer you get the log2b(2^1000) = (2^a)^1 = 2^1, then third layer you get 2^1000 = (2^b)^(2^a) = 2^(b * (2^a))
It's a bit odd here but equating the exponents from the last step we get, 1000 = b * 2^a and then since a na db are positive you just identify all powers of 2 that divide 1000, and sum em up to get 881

#

the only hard part is actually finding all the pairs and summing them

orchid urchin
orchid urchin
#

show me the work

#

massive typo

round geyser
#

Okay so

#

I’ll start with log_2^b (2^1000) = 2^a

#

Move the base under 2^a

#

Now it’s 2^1000 = (2^b)^(2^a)

#

Same base can cancel

#

1000=b^(2^a)

#

We know 1000 is 10^3

#

So it’s 10^3=b*(2^a)

orchid urchin
round geyser
#

Yea

#

It is

#

I’ll continue

round geyser
round geyser
#

You see

#

b = 5^3=125 and a=3

orchid urchin
#

yeah so far I agree

round geyser
#

You add them

#

3+125=128

orchid urchin
#

thats just one pair

#

a = 3 and b = 125 which sums to 128

#

a = 2 and b = 250

#

a = 1 and b = 500

#

501 + 252 + 128 = 881

#

neat relationship btw

round geyser
#

Thanks

round geyser
orchid urchin
#

lol

orchid urchin
# round geyser

im surprised thats a comp math problem, ig it makes sense though since u have to find pairs of numbers and sum them up which is unusual but I feel like it is very straightforward

round geyser
#

Yep

#

And I notice a pattern

acoustic galleon
#

very cool pattern

round geyser
#

When a is increased b will be decreased

#

When a is 1 to 2, b is 500 to 250

keen delta
# round geyser

de moivre's theorem
1+i=sqrt2cis45
so sqrt2^28 * cis(45*28mod360)
and then u get there

round geyser
#

What’s cis

#

And what’s mod

orchid urchin
#

mod is modulus

keen delta
orchid urchin
#

like 5 % 3 = 2

#

it shows the remainder

keen delta
round geyser
orchid urchin
#

except for 0 = x

keen delta
# round geyser What’s cis

you can also take everyone's advice and square it once, (1+i)^28=((1+i)^2)^14=(2i)^14 which as you know is not going to be imaginary

round geyser
#

Yep

keen delta
#

I never remember where the = and > goes

orchid urchin
#

and it can't be negative

keen delta
# round geyser Oh

in general u can do their tactics but for more weird problems on that I suggest doing de moivre's theorem

orchid urchin
#

if u cehcking if its a even or odd num

keen delta
#

because

orchid urchin
keen delta
#

even numbers - even numbers = even number and 2 and 2 are both even

#

frfr

orchid urchin
#

show proof

keen delta
#

idk I don't do discrete meth

keen delta
orchid urchin
#

what about -0

keen delta
# orchid urchin show proof

let m, n be any positive integer where m>n
2m-2n=2(m-n)
since it is divisible by 2 and m-n is positive, it's a thing yeah
2n-2n=0

keen delta
orchid urchin
orchid urchin
haughty crown
keen delta
haughty crown
potent slate
#

Or I might be wrong

#

The modulus might also be the specific number you divide by to find the remainder, I guess

#

Or something like that

orchid urchin
potent slate
#

sqrt(a^2 + b^2)???

orchid urchin
potent slate
#

for a complex number a + bi

orchid urchin
#

yeah and if u think about it its the same for x,y coords

#

non complex or rect coords

potent slate
#

True

orchid urchin
#

whatever u want to refer to them as

#

makes it easy to convert them to polar as well

potent slate
#

Mhm

drowsy trout
#

yall tryna read an exploratory note?

fossil kindle
drowsy trout
#

a dyadic kinda polynomial and quadratic sequence

barren horizon
#

Plot the points on a graph of the factored polynomial $p(x)=4(x-6)(x+3)(6x-1)(1x+2)$

obsidian monolithBOT
uncut mulch
#

how much detail is required?

barren horizon
#

Thats easy stuff

#

Its called precalculus but its easy

#

Just algebra at that point

eager meteor
#

Yo

#

Have we solved the dream integral?

#

And if yes, how?

orchid urchin
#

according to the internet

eager meteor
#

K thx

#

Also…

#

Is there a proof for squeeze theorem?

limber junco
#

it is left as an exercise for you to prove

#

Just use epsilon delta definition

eager meteor
#

But I am in 9th grade

#

But I’ll try

#

Thx

robust terrace
last palm
#

Guys, is there any website kinda thing where i can find calculus questions regularly??

fossil kindle
#

what is a squeeze theorem

echo sinew
fossil kindle
#

ig bro

#

not falling for ts again

hushed sphinx
#

What do you mean "falling for"?

#

The embed looks like the site is probably more than a bit snarky, but just seeing the embed itself should give you more than enough clue to understand Alberto's point without actually following the link ...

jolly karma
#

Hey chat how does one determine the direction of a parabola (or which variable changes) from this state?

fresh jay
last palm
#

Um write the equation with x square and its term on side side while keeping y on other side then its something like
Y=1/2(x)^2+5x+59
This proves the parabola is opening upwards and u can find its vetex by using (-b/2a,-D/4a)

#

Then find the y intercept and trace the graph

#

Also if x is squared term parabola opens up or down and if y is squared it opens left or right depending on conditions , here it opens up as x square is positive