#help-49

1 messages · Page 169 of 1

lyric charm
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could be some stupid arithmetic error

molten bay
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A little bit

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Give me some time

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@lyric charm

lyric charm
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where is -1/2 * -2 * x * x^3/6 from the expansion of -1/2(x - x^3/6)^2?

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oh wait no i do see the x^4/6

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it disappeared afterwards tho it looks like

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wait a minute...

molten bay
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Ohh hang on

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1/6

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I got it

lyric charm
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i mean the x^6 term should have been trashed also

molten bay
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@lyric charm

lyric charm
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you trashed too much but this time you were lucky

molten bay
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What do you mean by trashed?

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If i take only one term of it then

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(1-x^2/2-1+x^2/2)/x^4 which is 0

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.close

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#
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hybrid sage
#

can someone help me do just the number and algebra row in the table provided given the instructions included about statistics Measures of Position and Central Tendency

lyric charm
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have you done anything thus far

hybrid sage
lyric charm
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have you sorted these things in ascending order

hybrid sage
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but i'm not sure if its right since i've only tried

lyric charm
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ok im gonna take your word for it that the median is correct

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so now what else do they want you to find

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the quartiles?

hybrid sage
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can you help me correct the table

lyric charm
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id like to see the original data sorted in ascending order and ungrouped

lyric charm
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dont rly wanna do it myself cause it's a bit energy-consuming

hybrid sage
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do i still have to tally it?

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Ascending Order: 20,28,28,32,32,32,36,36,36,36,44,44,44,48,48,48,48,48,48,52,52,56,56,56,60,60,60,64,64,64,68,68,72,72,76,80,84,84

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is that good enough??

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what's next??

lyric charm
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ok so that's 28 data points

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20,28,28
that's 3 points that go in the 20-29 class interval

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and you put 2 as that interval's frequency

hybrid sage
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its confusing 😭

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what else did i miss

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wait

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is it correct that i can do up until 89 if the highest interval is 84

lyric charm
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the highest score you mean?

hybrid sage
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i corrected it

lyric charm
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ok sorry im finding myself too unfocused to continue looking at this

hybrid sage
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20, 28, 28, 32, 32, 32, 36, 36, 36, 44, 44. 44, 48, 48, 48, 48, 52, 52, 52, 56, 56, 60, 60, 64, 64, 64, 68, 72, 72, 76, 80, 84, 84

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cf = 33

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i fixed it

midnight plankBOT
#

@hybrid sage Has your question been resolved?

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stable halo
#

this is gonna sound completely stupid, and i know this is more data sci but idk whhere elsr to ask, but if i have a bunch of data points as shown above, how would i get the x coord at which the straight line becomes now a line with a gradient.?

winged maple
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as in if you drew a curve of best fit, the point when it stops being "basically straight" and starts being "basically curved down"?

stable halo
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i dont want to just eye it as it would be cheating

winged maple
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and I assume you want more than just eyeballing it

stable halo
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even though trhat would be pretty easy

winged maple
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yeah okay
fit a quadratic (or other) curve to the data, get the equation
differentiate it, solve for when the gradient becomes sufficiently negative (i.e. it's curving down enough to be "actually decreasing")

stable halo
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Yea that could work

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thanks

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but like

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there is so much noise

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how would i fit a curve to that data

winged maple
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honestly I would just not bother with that last step - fit a curve and eyeball it

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choosing a threshold as to when you deem it sufficiently "curved" is eyeballing anyway

stable halo
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Yea exactly

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my guess is i might need to use some machine learning stuff

winged maple
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yes

stable halo
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which is way out of my grade

winged maple
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are we talking, excel/google sheets level of paygrade here haha

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because you just want a (quadratic) regression

stable halo
winged maple
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as in yes, how do you have this data

stable halo
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or can excel do stuff like this

winged maple
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yes

stable halo
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for my physics project, atomic microscope needle and voltage stuff

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its for my undergad bsc

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so pretty mathy

winged maple
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curve of best fit in excel or quadratic regression in scipy

stable halo
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probably

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use scipy

winged maple
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yeah, it'd be better (for academic project purposes) to do this thoroughly

stable halo
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Yea

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thats also why ML is out of my range like i probably could learn not worth the effort though

winged maple
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yeah I'm suggesting reaching for "ML" in teh very simple sense - regression curves

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no need to train anything or w/e

stable halo
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Yea i can do regression

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i did non linear regrssion using euler newton method

winged maple
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fit the curve with scipy, calculate the x values that are deemed sufficientyl curved for a range of threshold values, and then report your findings as that interval in some way. makes it more mathy than just "I picked this gradient because idk"

stable halo
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for my group project

winged maple
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you know more than me, go for it

stable halo
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ahah that was a mess to leanr as a physics student

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but thanks for the help

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molten bay
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Any ideas?

midnight plankBOT
molten bay
hasty haven
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do u know ur double angle for cos? @molten bay

hasty haven
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we’re gonna wanna use u-sub to make it simpler

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what form of double angle would allow for a simpler du? @molten bay

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dusty portal
#

Let $a_1, a_2\ldots a_n$ be a strictly increasing sequence such that $a_n>0$ and $a_{2n}=a_n+n$. It is known that if $a_n$ is prime, then $n$ is prime. Find, with proof, the value of $a_{1993}$.

grand pondBOT
dusty portal
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!status

midnight plankBOT
#
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
dusty portal
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1

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Literally all I know is that a_0 is 0

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a_2=a_1+1 is prime so that means a_1 is composite

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Literally nothing else

runic hamlet
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the condition a_2n = a_n + n combined with the fact that the sequence is strongly increasing is very limiting

runic hamlet
dusty portal
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I don’t know if I can use the converse or not

runic hamlet
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why should you be able to

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thats not how that works

dusty portal
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Exactly 💀

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So I’m essentially stuck

dusty portal
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What do you mean by that

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“Very limiting”

runic hamlet
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it heavily restricts the possibilites of what a_n could be

dusty portal
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Oh, ok

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But I can’t find it shiver

runic hamlet
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what does it say about a_2, a_3, a_4

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ah wait I assumed that the a_ns are integers

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I suppose thats not given

dusty portal
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Nope

runic hamlet
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well they probably fucked up when writing the problem

dusty portal
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Wait nevermind lol

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It says positive integers

runic hamlet
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surprise

dusty portal
runic hamlet
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yes

dusty portal
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I’m in class so I can probably explore this

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I’ll come back in god knows how long

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I have a lab to do

runic hamlet
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you are basically done

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you just need to find c

dusty portal
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Ok

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0?

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a_0=0

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Nevermind

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Yeah I’ll figure it out

runic hamlet
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(a_0 doesnt even exist)

sharp wave
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is a0 even defined?

dusty portal
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Yeah

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Aight I think my brain is fried but I got it

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I think a_n=n is a solution anyways

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If a_n is prime then n is prime

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So a_{1993}=1993

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Bruh gg

runic hamlet
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why is a_n=n the only solution

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why not a_n=n+12037017569123123

hasty haven
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bc 2(n+c) ≠ 2n + c + n

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well

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it is

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but only if c=0

runic hamlet
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a_2n = 2n+c, an+n = n+c+n

hasty haven
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that’s so true actually

sharp wave
runic hamlet
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it does not say that

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it says if a_n is prime then n is prime

sharp wave
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oops, but i think you can find a non prime n for which an becomes prime

midnight plankBOT
#

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warm island
midnight plankBOT
warm island
#

Let f: AB -> CD be the projection of points in AB to CD
Let x be the point where pojections are made in AB, for each point x in AB we can draw a line to CD which intersects a unique point Y.

Thus we have f(x) = y. this is one to one since if we have x1 and x2, and they mapped to the same y on CD then the projection would make no sesnse. this is also onto since all points in AB will project to CD. Therefore this is a bijective mapping

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did i answer this? lol

midnight plankBOT
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@warm island Has your question been resolved?

placid spoke
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projected how? if you just draw a line from AB straight down to CD, f is not onto

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since the length of CD is larger than the length of AB

midnight plankBOT
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@warm island Has your question been resolved?

warm island
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I'm guessing there's some sort of relationship I can make idk

placid spoke
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you can actually pretty easily make a linear relationship between the two.

if you assume x goes from 0 to L and y goes from 0 to M (with L < M) construct the line that goes from (0,0) to (L,M)

warm island
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alright ill think about it im doing this just for fun '

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true egret
#

Totally stuped on this problem from Real Analysis. I've got two vectors x and y, both in R^n. I've got an affine function Ax+b, with some matrix A and bias vector b that I don't know. I'm supposed to optimze A and b so that | |y-(Ax+b)| |^2 is minimized. I've got no clue how to do this. I don't know how to differentiate with respect to a vector or a matrix. Need some direction on what I'm supposed to be doing here. Book is useless and I don't want to spend 2 days barking up the wrong tree researching this.

true egret
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no

wary thorn
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Well

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If you get to choose A and b

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Choose A so that Ax=y has a solution and let b be the zero vector

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Then it's minimized

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I assume that that's not the intention of the question though, so what do you mean "optimize A and b"?

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the extrema of f(x)=||y-(Ax+b)||^2
will have grad f (x) =0

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aswell

midnight plankBOT
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@true egret Has your question been resolved?

true egret
#

What they literally ask is "find the affine function g(x)=ax+b such that the sum (j ranging from 1 to the number of dimensions) of (y_i-g(x_j))^2 is minimzed." I think that's equivalent to minimizing | | y-(Ax+b) | | ^2

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But then it's such a stupid question... that can't be what they're fishing for

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I don't know how to take the gradient of a function that has a matrix in it

midnight plankBOT
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@true egret Has your question been resolved?

midnight plankBOT
#

@true egret Has your question been resolved?

humble wolf
humble wolf
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upbeat plinth
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upbeat plinth
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lethal path
grand pondBOT
upbeat plinth
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polar star
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,w derivative of 2x^(5/4) wrt x

lethal path
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yes you should be doing sqrt(1 + (y')^2) instead

upbeat plinth
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lethal path
#

yes and then try taking sqrt(1/4) = 1/2 out of the square root

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lethal path
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lethal path
upbeat plinth
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lethal path
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^ this is how I would do it

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steep mirage
midnight plankBOT
steep mirage
#

Ik one of the factors is (x-1)

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But idk if I gotta find a new other one to know what to divide this by or what I do from here

nimble copper
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If you haven't been taught any methods to solve a cubic then you have to find another factor

lethal path
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except if you can spot if the cubic is a perfect cube or some other special case, mainly that and a^3 + b^3 or a^3 - b^3

steep mirage
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We were not taught that

lethal path
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don't worry if you can't spot these special cases though

steep mirage
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So prob shouldn't do on exam

lethal path
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yep exactly

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exam just wants you to guess till you get p(x) = 0 again

steep mirage
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Ok

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What does the p stand for

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Btw

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This random but yk

lethal path
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p stands for polynomial!

steep mirage
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Fancy

lethal path
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f stands for function

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g is also a function and h usually

steep mirage
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Ig that makes sense 💀

lethal path
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cause of the alphabet haha

steep mirage
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Yeah 💀

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Idk

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I did one of these questions to study

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Got it first try

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Idk if I wanna do more

steep mirage
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For this 7a

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Would I just set x has 2

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And make it = 0

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The remainder theorem I think it's called

lethal path
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so that's actually called the factor theorem, but that's just the remainder theorem with remainder = 0

steep mirage
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Ok

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Another question actually

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For 11

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Would I just start by diving by -6

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Theater that factor it

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To get my other 2 factors

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Which is the L and W

lethal path
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,calc (-6)^3 + 14(-6)^2 + 63(-6) + 90

grand pondBOT
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Result:

0
lethal path
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or x + 6

steep mirage
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Okay

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Yep

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Ty

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All for now

lethal path
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np!!

dim solar
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but will that result is zero right ?

lethal path
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yeah like just making sure the question wasn't broken

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I know that it has x + 6 already

dim solar
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oh okay

steep mirage
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Math fun

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When you actually understand it

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But I also hate studying late

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So idk

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But Ty guys

dim solar
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it's about the journey not the goal bro

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just enjoy when things getting hard that what i mean

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and the best times is when getting the answer

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if you don't need the channel to forget to close it @steep mirage

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don't*

steep mirage
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Actually

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Got 1 more thing 💀

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How do you find the multiplicity

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Wtf is multiplicity

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Can someone give an example

dim solar
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bro try to revisit the lesson first 💀

steep mirage
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I did

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But no where does it say how you find the multiplicity

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My teachers notes suck ass

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I was gone at an appointment

dim solar
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i'am in a middle of a session i will finish it and try to figure it out with you

steep mirage
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Actually

dim solar
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can i ask smth personal tho

steep mirage
dim solar
#

u are at g12 right

steep mirage
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I just don't understand how you find the multiplicity when you aren't given a picture

steep mirage
dim solar
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is that SAT or just regular school work /

steep mirage
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Regular

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Test tmr

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This is the hardest math class my school offers

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And it ain't even bad

dim solar
steep mirage
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Nah it'll be aight

dim solar
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without so much yapping im gonna finish quickly and try to solve it with you

steep mirage
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Okay

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Just wist 1 moment

midnight plankBOT
#

@steep mirage Has your question been resolved?

dim solar
#

sorry bro i didn't figure it out myself

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@steep mirage

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median ridge
midnight plankBOT
median ridge
#

im sorry- what does that mean?

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like using x measured in radians??

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nvm im freaking dumb

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.close

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lethal path
median ridge
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like that sounds weird

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but if u think of it with the unit circle, it makes no sense to use degrees

lethal path
solid iris
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degree and radian are unitless

lethal path
lethal path
median ridge
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.reopen

midnight plankBOT
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median ridge
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ok but now im a little bit

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with this limit

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sinx/x

normal prawn
median ridge
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am i supposed to be imagining a graph here or is it just an expression?

lethal path
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well the graph of (sin x)/x is pretty tricky

median ridge
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yeah

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thats why im kinda

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confused

solid iris
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hmm yes dimensionless is better

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for the physics minded

median ridge
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if its the graph of it, it makes me confused but expression wise is different

lethal path
median ridge
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look idk

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but with the graph, there is a point where x = 0

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which is 0/0 but its still there in an actual graph so it confuses me to use radians

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because x = pi is an actual point on the graph

normal prawn
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I mean, at x=0 function is not defined

median ridge
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obviously i can scroll forever but shouldnt there be a more obvious circle to show that theres a hole there?

lethal path
lethal path
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if you hold and click on the graph at exactly x = 0

normal prawn
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Loll

lethal path
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it does show the white circle

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but not otherwise

normal prawn
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truee

median ridge
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oh okay

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i get it now thank you

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do you think it was kinda a bad example to use orrr?

lethal path
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no!

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it's really good you're thinking about limits and how that differs from if a function is defined at that point or not

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that was the whole point of your original message

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what your textbook or notes wrote there

median ridge
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okay

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they put a photo of the graph below but i still wouldve liked to see a hole lmao

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.close

midnight plankBOT
#
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prime garden
#

Expand a^x.

midnight plankBOT
prime garden
#

As a sum of powers of a.

wary thorn
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What

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What is your doubt

normal prawn
lyric charm
#

!xy

midnight plankBOT
#

Please show the original problem, exactly as it was stated to you, with the entire original context. A picture or screenshot is best. If the original problem is not in English, then post it anyway! The additional context might still be helpful. Do your best to provide a translation.

prime garden
#

Let a = 5.
We need to expand 5^x.
Let 5^x = k
Then (k - 1)/(a - 1) = 1 + a + a^2 + a^3 + ........... + a^(x-1)
where k = 5
a - 1 = 4
(k-1) = 4 + 4a + 4a^2 + 4a^3 + 4a^4.................... + 4a^(x-1)
k = 5 + 4 * 5^1 + 4 * 5^2 + 4 * 5^3 + 4 * 5^4.............. + 4 * 5^(x-1)
So 5^x = 5 + 4 * 5^1 + 4 * 5^2 + 4 * 5^3 + 4 * 5^4.............. + 4 * 5^(x-1)

lyric charm
#

???

#

what are you REALLY trying to do?

wary thorn
#

he asked the writign sir to do this

#

i can tell

wary thorn
prime garden
#

I guess one can find 5^x from 5^(x-1)

normal prawn
prime garden
#

No

normal prawn
#

That's exactly what u did

prime garden
#

It's useless

normal prawn
#

bruh

#

then?

prime garden
#

!status quo

midnight plankBOT
#
What step are you on?
1. I don't know where to begin.
2. I have begun but got stuck midway.
3. I got an answer but I was told that it's wrong.
4. I got an answer and would like my work checked.
5. I have a question about someone else's work/solution.
6. I have completed the problem and don't need help anymore. Thank you.
7. None of the above
prime garden
lyric charm
#

!done

midnight plankBOT
#

If you are done with this channel, please mark your problem as solved by typing .close

prime garden
#

Ikr

#

.close

midnight plankBOT
#
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midnight plankBOT
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empty ivy
#

Hi I dont get part i like how do you start

midnight plankBOT
sage helm
#

hmm

lethal path
sage helm
#

[ \f{\sin a + \sin b}{2} \geq \sqrt{\sin a \sin b} ]

grand pondBOT
sage helm
#

on a restricted domain

lethal path
sage helm
#

no it doesn't lol

#

it's just the AM-GM

sage helm
lethal path
#

ah I know ok let's stop here and let them think then'

sage helm
lethal path
#

nah your idea's better

tawdry laurel
#

am gm yay

#

Hi south

lethal path
sage helm
lethal path
#

the way to fix that is to use the rearrangement, $(\sin a + \sin b)^2 \ge 4 \sin a \sin b$

grand pondBOT
sage helm
#

yeah

#

that's always true

#

actually this might be it

#

sum of sines inside

lethal path
#

yeah then Jensen's or something

grand pondBOT
empty ivy
lethal path
#

it's useful for situations like this where you want to compare f(x + y) and f(x) + f(y)

slim eagle
#

u gotta see the graphs

empty ivy
#

Kk

#

Okay thanks everyone

#

.close

midnight plankBOT
#
Channel closed

Closed by @empty ivy

Use .reopen if this was a mistake.

idle glen
# grand pond **south**

you can go ahead and try to apply Jensen's but I think that is an overkill, you can start from here and prove 1 from algebraic manipulation and then prove 2 from 1 and some more inequalities manipulation
(I feel this is the expected solution)

midnight plankBOT
#
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novel dune
midnight plankBOT
novel dune
#

how do i graph this?

winged maple
novel dune
winged maple
#

break it into 2 pieces, and differentiate each piece

novel dune
#

um

#

how do i do that

winged maple
#

well it has a straight part and a parabola part, right

novel dune
#

yes

winged maple
#

so the gradient for the straight part would be...

flat spire
novel dune
flat spire
#

yr 11?

novel dune
flat spire
#

i c

#

u gonna do 4u?

novel dune
#

prolly not if im struggling on this

flat spire
#

u got this gng

novel dune
north robin
# novel dune 😭

Find the equation for the straight line graph and the parabola separately

novel dune
#

or can i do with just like points

pale vapor
#

how will you do it with just points

novel dune
#

no idea

pale vapor
#

how will you so it with equation

novel dune
pale vapor
#

oh

#

do you know what derivatives are

novel dune
#

yeah

#

the gradient of the tangent of a line

pale vapor
#

yeah

#

do you know how to find derivative of a given equation

novel dune
#

yes

#

i just dont really get how to turn a graph into the derrivative of the graph

pale vapor
#

so you can find the eqn of the parabola and differentiate it

novel dune
#

okay

#

lemme find it rq

#

y= x^2-2x?

pale vapor
#

yeah

novel dune
#

and then the derivative is 2x - 2

pale vapor
#

yes

#

now the break the graph into two parts

#

-infinity to -2 and -2 to infinity

novel dune
#

huh

pale vapor
#

basically the line and parabola

novel dune
#

um

topaz urchin
novel dune
#

its 4

topaz urchin
#

yeah so

#

from x = -infinity to x = -2

#

it's a straight line right

novel dune
#

uh

#

yeah

#

oh yeqh

#

i get it

#

yeah

topaz urchin
#

and the slope is 4

#

so you will plot y = 4 from x = -infinity to x = -2

novel dune
#

do i put open circle at -2

topaz urchin
#

a sec

#

back

topaz urchin
novel dune
pale vapor
novel dune
#

would this be right

pale vapor
#

plot y = 2x - 2 from x=-2 to x=infinity

novel dune
pale vapor
#

yeah seems right

#

idk about the circle part though

novel dune
#

o

topaz urchin
#

should be open

novel dune
#

whats the curve called when its like all wiggly

topaz urchin
#

wdym by that

novel dune
#

like this

topaz urchin
#

that's the graph for a cubic function

novel dune
#

oh

#

thanks

#

how would i do this

#

😭

north robin
novel dune
#

1,0

north robin
#

You’re question is for part a right?

novel dune
north robin
#

Let’s go over a first

#

What do you think the question is asking you?

novel dune
#

prove that the stationary point of infelction is at x=1

north robin
#

In reference to the graph

novel dune
#

yes

#

can i just say that the vertex of the parabola is 1,0

north robin
#

You need to justify the fact that the the stationary point is actually a stationary by referencing the graph

#

So you need to consider the gradient function’s behaviour at the point (1,0)

#

And link that to the graph

novel dune
#

wel

#

the gradient is 0

#

at 1,0

#

since its just a straight line on the x axis

north robin
#

Therefore

novel dune
#

since the parabola is concave down its maximum turning point is at 1,0 and since the gradient at 1,0 is 0 its also a stationary point

#

?

north robin
#

Pretty much yeah

novel dune
#

how would i graph it

#

?

north robin
#

You talking about b?

novel dune
#

yes

north robin
#

Consider the derivative right

#

We know it’s going to be an increasing function up until the stationary point then it’s gonna start decreasing

novel dune
#

uhh

#

yeah?

north robin
#

Wait nvm the derivative is constantly negative right?

#

So how do you think the original graph is going to look like?

novel dune
#

isnt the original grpah the one they gave?

north robin
#

No that’s the derivative of the original

novel dune
#

oh

#

i dont know

north robin
#

It’s negative so the values of the original function are always going down right?

novel dune
#

yes

north robin
#

Ok and we know that the original function has the value -3 at 1

novel dune
#

yes

north robin
#

We know that the derivative is quadratic, so what type of function must the original be?

novel dune
#

um

#

decreasing

#

idk

north robin
#

Right but what type of polynomial

#

It’s a cubic function

#

The graph that you said was all wiggly

#

Since we know that the original is cubic and it has the point of inflection at that point.

#

Also it’s constantly decreasing you can put these together to make a sketch of the graph

novel dune
#

😭

north robin
novel dune
#

if its constanly

#

decreasing

#

do i just start from otp left

north robin
#

Yes

#

Then it has a point of inflection at the point that was mentioned

novel dune
#

and then wat

#

is it just 1 point of inflection

north robin
#

Yes since it’s the only stationary point

#

You know what a point of inflection is right?

novel dune
#

its like

#

where the concavity changes

#

so would i draw it

#

from the top left

#

and then it passes through

#

1,0

#

and hten to the bottom right

north robin
#

Not 1,0

#

That’s for the derivative

novel dune
#

oh

#

for 1,-3

#

it it like

#

idk

#

can u just give me the asnwer atp

north robin
#

You have the answer

novel dune
#

okat

#

okay

#

is this right

north robin
# novel dune

Yeah, the slopes aren’t that steep but since it’s a sketch it’s fine

novel dune
#

okay

novel dune
north robin
#

You need to look at the second derivative or take values of the derivative of either side of the stationary point

novel dune
#

well

#

i did the 2nd derivative

#

and i have the x values of the stationary points

#

what do i do now

north robin
#

Plug the x value into the second derivative then use this

novel dune
#

okay

last arch
#

The one for stationary inflection points

novel dune
#

holy crap man why this hw so hard

north robin
last arch
#

Then you'd have to use the first derivative test

midnight plankBOT
#

@novel dune Has your question been resolved?

novel dune
#

no

north robin
#

Sorry I am a bit busy as I have a test in like 45 mins

novel dune
#

goodluck

topaz urchin
novel dune
topaz urchin
#

do you know the condition

#

for which a function is increasing

novel dune
#

if its greater than 0

#

?

topaz urchin
#

yeah if the derivative

#

is greater than 0

#

so differentiate that equation

novel dune
#

i did

#

i got the x values

#

of

#

-2,-1 and 2

#

but idk what to do nwo

topaz urchin
#

do you know how to solve

#

(x+2)(x+1)(x-2) > 0

novel dune
#

no

#

idk

topaz urchin
#

hmm you'll have to look up that first

#

because that's how you'll get the values of x

novel dune
#

well

#

dont u just equate

#

it

#

to

#

0?

topaz urchin
#

no, the condition is that derivative should be greater than 0

#

not equal

novel dune
#

oh

#

well

#

is it just

#

x > -2

#

x > -1

#

and x > 2

topaz urchin
#

no no that's not how you solve these

novel dune
#

oh

#

how do u solve them

topaz urchin
#

so draw a number line

novel dune
#

okay

#

done

topaz urchin
#

our factors are

#

i mean

#

our equation

#

is

#

12x^3 + 12x^2 - 48x - 48 > 0

#

right

novel dune
#

yes

topaz urchin
#

yeah so if we divide it by 12 we get

#

x^3 + x^2 - 4x - 4 > 0

novel dune
#

yeah

topaz urchin
#

so you get

#

(x+2)(x+1)(x-2) > 0

#

right

novel dune
#

yes

topaz urchin
#

yeah so plot -2, -1 and 2 on the number line

novel dune
#

okay

#

i did it

topaz urchin
#

now we have 2 on the right side

#

if you put x greater than 2

topaz urchin
novel dune
#

yes

topaz urchin
#

so we want x = 2 to infinity

#

now we'll look at

#

x between -1 and 2

novel dune
#

yes

midnight plankBOT
#

@novel dune Has your question been resolved?

topaz urchin
#

You can try it yourself first

#

Then we can cross check

midnight plankBOT
#
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stoic garnet
#

Can't we have well defined functions which are not expressible as a expression but instead is better found in other ways

prime garden
#

an expression*

grand pondBOT
lyric charm
#

famously this integral is not expressible via elementary functions of x

prime garden
stoic garnet
#

But can't be expressed using any symbols whatsoever without actually making like a lot of cases

lyric charm
#

seems so

#

tho i have not looked into it

prime garden
#

Ok

lyric charm
prime garden
#

give an example

stoic garnet
#

Given input and a description of the function

#

How to find output

midnight plankBOT
#

@stoic garnet Has your question been resolved?

stoic garnet
#

Is my question off base

#

<@&286206848099549185>

#

.close

midnight plankBOT
#
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midnight plankBOT
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spark gazelle
#

how could i do this on a calculator?

midnight plankBOT
polar star
#

R_3 is just for n = 3

#

you can easily compute it using 3 subintervals

#

but regardless, can u shwo the whole question?

#

u may not have to use a calculator at all

spark gazelle
#

this is the whole question

polar star
#

"which of the following statements is true"

#

show the statements

spark gazelle
#

oh sorry

#

idk my test is with calc so i thought i might as well as try to use it to the best of my ability

#

ik its an overestimate

#

bc its a right riemann sum

polar star
#

and because it is increasing

spark gazelle
#

ig itd be 13.133?

polar star
#

nah use calculator for that

spark gazelle
#

how tho

polar star
#

its hard to tell just by inspection

#

u got casio?

spark gazelle
#

uhh

#

no

#

ti89 titanimu

polar star
#

okay fine

#

u will have to do it manually then i guess

spark gazelle
#

yeah we're not allowed to use any other calculator

polar star
#

do u know an expression for the right riemann sum

#

its gonna be ∑f(a+kdeltax)deltax

spark gazelle
#

uhh

polar star
#

u compute that from k = 1 to 3

#

so u just add (f(a+deltax)+f(a+2deltax)+f(a+3deltax))deltax

#

a being lower bound, delta x being (b-a)/3

spark gazelle
#

tf

#

uh

polar star
#

do u know what riemann sums are?

spark gazelle
#

i mean vaguely

#

i just kind of know its the area under a curve

polar star
#

do u know how to convert that integral to its riemann sum?

spark gazelle
#

nope

#

oh wait

#

i can just plug the equation into

#

a plot and do y function

limpid vigil
# spark gazelle nope

[\int_{a}^{b} f(x)dx =\lim_{n \to \infty } \sum_{i=1}^{n} f(x_i)\Delta x ] where (\Delta x =\frac{b-a}{n} ,x_i=a+i\Delta x)

grand pondBOT
#

HeavensJester

spark gazelle
#

oh

#

ok so the definition i get

#

now how to plug into a calculator to actualy solve though?

limpid vigil
spark gazelle
#

nvm i just put it into plot graph

#

and did it from there

#

i think doing summation is just overcomplicating it

limpid vigil
#

so something like [\sum_{i=1}^{1000} f\left(a+ i\cdot\left(\frac{b-a}{1000}\right)\right) \frac{b-a}{1000} ]

grand pondBOT
#

HeavensJester

spark gazelle
#

i think

#

that might be overcomplicating the problem a bit

#

.close

midnight plankBOT
#
Channel closed

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limpid vigil
midnight plankBOT
#
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lament fox
midnight plankBOT
lament fox
#

I don't know how to approach this

cedar mason
#

i mean

#

one would assume the numerator factors out

#

,wolf give factors of (3x^5 - x^4 + 2x^3 -12x^2 -2x +1)

cedar mason
#

thanks wolffram

#

yeah that's weird

cedar coral
#

this seems like you need to decompose it to simple fractions

#

start by factoring the denominator for that

#

you can start with (x^3-1) = (x-1)(x^2+x+1), so you'll have 4 fractions

midnight plankBOT
#

@lament fox Has your question been resolved?

lament fox
cedar coral
#

so?

lament fox
#

I don't want to do all of that

#

I doubt they would make me do that

cedar mason
#

yeah

#

,wolf expand (1 + x + x^2) (1 + x + x^3)

cedar mason
#

okay thats not it

#

cmon wolf send help

tough shale
#

,w (3x^5-x^4+2x^3-12x^2-2x+1)/(x^3-1)

tough shale
#

C'mon, I need the quotient and remainder

#

,w quotient and remainder of (3x^5-x^4+2x^3-12x^2-2x+1)/(x^3-1)

midnight plankBOT
#
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midnight plankBOT
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chilly cobalt
#

Let $a$ be a real number satisfying $\$
img

If the set of possible values of $a$ is $(x,y]$ for real numbers $x,y$. What is the value of y - x? (correct to 4 decimal places.)

grand pondBOT
#

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

chilly cobalt
#

can someone help me? i have no idea where to begin

#

please dear math gods, bless me with thee knowledge😭

cedar mason
#

the latex is weird too

small jasper
chilly cobalt
small jasper
#

Yeah that’s the interpretation that I went with

chilly cobalt
#

im not good with this type of stuff xd

small jasper
#

But what can you conclude about the floors (as in what are their values)

chilly cobalt
#

a>1?

small jasper
#

I’m asking about the values of these

chilly cobalt
#

oh

#

floor(2009/a) = 2008 and floor(2552/a) = 2551

small jasper
#

mhm

chilly cobalt
#

so like

#

next thing might be inequalities, i think?

small jasper
#

Yup

chilly cobalt
#

aaa ive never done this😭

#

2009 > 2009/a >= 2008, maybe?

#

YIPPE

#

give me a moment

#

1 < a <= 2552/2551

#

,w 2552/2551

chilly cobalt
#

.

small jasper
small jasper
grand pondBOT
#

Result:

1.000392003136
chilly cobalt
#

so the answer is 0.0004

small jasper
#

Mhm

chilly cobalt
#

tyy!!

#

,close

#

.close

midnight plankBOT
#
Channel closed

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midnight plankBOT
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ruby willow
#

yo can i get help

midnight plankBOT
ruby willow
#

<@&286206848099549185>

mossy moat
#

arcsine(0.59)

ruby willow
#

?

#

sorry im slow in the head

lyric charm
#

your calculator should have a button that says sin^-1 or something similar.

ruby willow
#

oh yeah

lyric charm
#

use it to calculate $\sin^{-1}(0.59)$.

grand pondBOT
mossy moat
#

this will give one answer

lyric charm
#

and also make sure the calculator is in degree mode.

ruby willow
#

its asking for 2 answers tho

lyric charm
#

do what i said first. that's going to be your part a.

ruby willow
#

ok i gt 36.1570082

limber grove
midnight plankBOT
# ruby willow <@&286206848099549185>

Please only use the <@&286206848099549185> ping once if your question has not been answered for 15 minutes. Please do not ping or DM individual users about your question.

lyric charm
#

round to nearest whole.

ruby willow
#

36

limber grove
#

uh

#

did you read the second part of the sentence

lyric charm
ruby willow
#

new to server

lyric charm
#

look at the graph now and see that it crosses the line y=0.59 in two points

#

one of them is the x=36° you just found

ruby willow
#

thats gotta be the one closer to 0

lyric charm
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the other is symmetric to it across the line x=90°

ruby willow
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yes

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how do i calculate the other one

lyric charm
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in other words the other solution will be 180-36

ruby willow
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how

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ok i got it ty

lyric charm
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sin(180°-x) = sin(x) always

ruby willow
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alr

midnight plankBOT
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@ruby willow Has your question been resolved?

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vocal briar
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can someone explain to me why my logic is wrong when I see, integral of cosx/sinx

vocal briar
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im not sure if i aksed this before bc i forget but i js did integral of (tanx)^-1

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but this doesn't get the right ans of ln|sinx| + C

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cuz integral of tanx^-1 is js ln|tanx| * (secx)^2 + C i think

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the correct way is to use u sub which i realize now

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but why is this way wrong?

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im aware it gives me the deriv as 1/ sinxcosx which is obv not cosx/sinx

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but i still dont see what is wrong with converting cosx/sinx to (tanx)^-1

vocal briar
bitter tide
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why not just do a substitution

vocal briar
#

no like ik you can

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but the first time i did this question i didn't

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so like im js not sure what is wrong with the method

bitter tide
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well u do get cotx, but thats just overcomplicating sum trivial

vocal briar
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ok but integral of cotx and tanx^-1 is diff tho

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like the method i mean

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not the ans

bitter tide
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well tan^-1 is arctan. if u mean 1/tanx, then thats cotx

vocal briar
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yeah

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but like i wanted to use ln

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cuz like 1/x would've been lnx

bitter tide
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well yea ud needa sub and then u get ugly stuff

vocal briar
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yeah but like can u show me how to do it that way anyway 😭😭

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im kind of confused on what to do after i get integral of tanx^-1

pale vapor
bitter tide
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ok lemme get sum paper, im rusty on integrals

vocal briar
grand pondBOT
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gamer75431

vocal briar
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which im not sure if thats right

pale vapor
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no send your wor

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k

vocal briar
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i js know that when you differentiate this you dont get cosx/sinx

pale vapor
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i can tell you where you went wrong

vocal briar
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heres what i did

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im not sure its much better than what i sent tho lol

bitter tide
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ok well i ended up after sub u=tanx with integral du/u(1-u^2)

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ah u cant apply ln to that

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it needs linear function on bottom

vocal briar
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ln doesn't apply to trig func?

bitter tide
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nope

vocal briar
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oh

pale vapor
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onlt integrak of 1/x i lnx

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only*

vocal briar
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ohh

bitter tide
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can be generalized to 1/ax+b

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ln(ax+b)/a

vocal briar
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oh okk

pale vapor
bitter tide
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well yea but u can skip that

pale vapor
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yeah

vocal briar
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right that makes sense since deriv would've been a/ln(ax+b)

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of F(x) = (ax+b)^-1

bitter tide
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deriv of ax+b is a

vocal briar
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no sorry i forgot to type it right lmao

bitter tide
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u dont sub the whole thing. the linear function to get 1/u

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then u can ln that

vocal briar
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wdym

vocal briar
bitter tide
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yeah

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ok lets say u have 1/(ax+b)

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integrate that