#Calc. 1 Chain Rule

1357 messages · Page 2 of 2 (latest)

oak jewelBOT
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AstroGuy

gloomy rock
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It’s a mix of product rule and chain rule

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If you can solve that then you can succeed in your exam

sour junco
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Isn't that just lovely

gloomy rock
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In the derivative part

sour junco
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Ok one second

gloomy rock
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Remember the steps

sour junco
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Okay

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do i have to simplify

gloomy rock
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No

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Actually you can’t

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You could do something but that will complicate the thing

sour junco
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I can't put the fractions together

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?

gloomy rock
sour junco
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oh i cant

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the first one doesnt have x in numerator

gloomy rock
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Just give me result as it is

sour junco
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i got

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1/3x^2+4 + 6x/3x^2+4

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or

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no

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ummmmm

gloomy rock
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No

sour junco
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😩

gloomy rock
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You were close tho

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I see you applied product rule correctly

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But chain rule is bad

sour junco
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Sigh

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What did I do wrong this time

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🥲

gloomy rock
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Let me go back:

$f(x)=xln(3x^2^+4)=uv$

u=x v=ln(3x^2+4)

So:

$f’(t)=u’v+uv’$

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

sour junco
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yes

gloomy rock
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Alright

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What is u’

sour junco
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then its 1 * ln 3x^3 + 4

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  • x * 6x/3x^2+4
gloomy rock
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No

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Give me u’

sour junco
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1

gloomy rock
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Alright now v’ requires chain rule which you may have a made a slight error when using it

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v=ln(3x^2+4) right?

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I stated that initially

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What is f(x) and what is g(x)

sour junco
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x

gloomy rock
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?

sour junco
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and ln(3x^2 + 4)

gloomy rock
gloomy rock
sour junco
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🥸

gloomy rock
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I am talking about f(x) and g(x) as in chain rule

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For v’

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Remember the steps

sour junco
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well

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x

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ok no

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OK WAIT.

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xln

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3x^2+4

gloomy rock
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No

gloomy rock
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u=x v=ln(3x^2*4) alright?

sour junco
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yes

gloomy rock
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Because of the product rule

sour junco
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yes it is

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yes

gloomy rock
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We have to apply

sour junco
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yes we do

gloomy rock
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Okay now you said u’=1

sour junco
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correct

gloomy rock
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Now v’ requires chain rule to be determined.

v=ln(3x^2+1)=f(g(x))

sour junco
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xoh

gloomy rock
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What is f(x) and g(x)

sour junco
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well ln

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f of x

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and g of x is 3x^2+4

gloomy rock
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Just write them f(x)=…. And g(x)=…

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But yeah you’re right

sour junco
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Okay

gloomy rock
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f(x)=ln(x)

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g(x)=3x^2+4

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What is f’(x)

sour junco
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1/x

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again

gloomy rock
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Alright. Now plug g(x) in f’(x)

sour junco
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1/ 3x^2+4

gloomy rock
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Yes

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Multiply by g’(x)

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Cuz formula is:

f’(g(x))g’(x)

sour junco
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so yeah

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6x / 3x^2+4

gloomy rock
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Yes !

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Alright keep it in mind now

sour junco
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right....... 😀

gloomy rock
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v’=6x/(3x^2+4)

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u=x

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v=ln(3x^2+4)

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u’=1

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Derivative of the main function is:

u’v+uv’

sour junco
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correct

gloomy rock
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Well now apply

sour junco
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well

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it is

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$f(x) = ln(3x^2+4) + 6x/3x^2+4$

oak jewelBOT
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Eve 🌷

sour junco
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LMAOOO

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It worked

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but technically

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what i did was

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make it into a fraction

gloomy rock
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Ohhhh you succeeded in writing in latex

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I am impressed

sour junco
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it can be a fraction too

sour junco
gloomy rock
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You forgot something

sour junco
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$f(x) = ln(3x^2+4) + x * 6x/3x^2+4$

oak jewelBOT
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Eve 🌷

gloomy rock
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6x*x=6x^2

sour junco
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Bro

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Oh my GODDDDD

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Ok hold on

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$f(x) = ln(3x^2+4) + 6x^2/3x^2+4$

oak jewelBOT
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Eve 🌷

gloomy rock
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There we go

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That’s more like it

sour junco
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BUTTTTT

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iT CAN BE

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$f(x) = 1/(3x^2+4) + 6x^2/(3x^2+4)$

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NO?

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wait that looks ugly

gloomy rock
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Let me write with parentheses

oak jewelBOT
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Eve 🌷

gloomy rock
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$ln(3x^2+4)+\frac{6x^2}{3x^2+4}$

oak jewelBOT
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AstroGuy

sour junco
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Ok show off

gloomy rock
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Ahahahah

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In paper you must write the parentheses

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So you don’t get lost

sour junco
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😩

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Yes master 🫡

gloomy rock
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Alright it’s finished

sour junco
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BUT

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NOOOOO

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FRACTION

gloomy rock
sour junco
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How

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Literally

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if u can do it

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to the second one

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why not the first one

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it can be a fraction too

gloomy rock
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Oh you mean putting everything on the same denominator

sour junco
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NOOOOOOO

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No

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two seperate fractions

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although

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not a bad idea yeah u can make it one fraction too

gloomy rock
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It’s gonna be a mess

sour junco
gloomy rock
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There will be squared terms everywhere

sour junco
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Ok ill just leave it like that

gloomy rock
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Nothing more to do

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But you seem to sometime get confused

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Always start by writing u and v

sour junco
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Sometimes?

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95% of the time im confused

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👍 😁

gloomy rock
sour junco
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the terms

gloomy rock
sour junco
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Yes

gloomy rock
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Then: u’v+uv’

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And you got the derivative

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Sometimes you don’t need product rule

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Because it’s one singular function

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Just chain rule

sour junco
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Well

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I won't be able to tell anyway ☺️

gloomy rock
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3x^2+3x

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No product rule needed

sour junco
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well thats just power rule yeah

gloomy rock
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ln(x^2-2)

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No product rule needed

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But chain rule needed

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You recognize f(g(x)) type of function

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It’s called « a composite function »

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x*ln(4x^2-3)

sour junco
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Ok i need to learn how to recognize that as well

gloomy rock
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Product rule + chain rule

sour junco
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yes

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so

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OH

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OK

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SOOO if its basically like

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Only two different types of derivatives

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then its chain

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if its more

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like within each other

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product is included

gloomy rock
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By multiplication

sour junco
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like

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how we had

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ok well actually yes nevermind i guess u do multiply it as well

gloomy rock
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If your function can be split into two functions: product rule

sour junco
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yes yes

gloomy rock
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If you notice that one of these two function is a composite function then chain rule as well

sour junco
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thats what i mean

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Yes

gloomy rock
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😊

sour junco
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Ok now it makes sense

gloomy rock
sour junco
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ANYWAY im sure its late for you and my brain is actually fried so at this point im just going to accept defeat for this exam

sour junco
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Tomorrow

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innn

gloomy rock
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How many time left before exam

sour junco
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17 hours?

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ish

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It's 4:20 here pm

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Tmrw the exam is at 9:00 ish

gloomy rock
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The thing is… i won’t be at peace if you don’t solve a derivative on your own

sour junco
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am

sour junco
gloomy rock
sour junco
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No it's not okay

gloomy rock
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Just solve one without my intervention

sour junco
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Get rest LOL I feel bad

gloomy rock
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And I’ll go rest

sour junco
gloomy rock
sour junco
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I'm at a point where i'll throw up if i look at another derivative

gloomy rock
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We’ve made many examples

sour junco
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I will have to nap soon then wake up at 1 am to cram hahahah

sour junco
gloomy rock
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Alright let’s say i give you one last function to derivate and if you succeed I’ll go off

gloomy rock
sour junco
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But we can try

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😁

gloomy rock
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$L(x)=3xln(2x^2+2x)$

silver girder
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Hello there

oak jewelBOT
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AstroGuy

gloomy rock
sour junco
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Ok, let's see

gloomy rock
gloomy rock
gloomy rock
silver girder
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Good, u

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What was the question

gloomy rock
gloomy rock
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Composite functions

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Chain rule

silver girder
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Hmmm

gloomy rock
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I gave many functions for training

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Are you alright ?

sour junco
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No.

gloomy rock
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You are solving it right now ?

sour junco
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Yes

gloomy rock
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Well tell me once you finish

sour junco
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wanna see

gloomy rock
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Im sure you can do it

sour junco
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what i got so far

gloomy rock
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Yeah

sour junco
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🥲

gloomy rock
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Show me

sour junco
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Ok

silver girder
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What was the function

sour junco
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I color coded so steps r easier to read

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I give up

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Sorry

gloomy rock
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But it’s the right answer

silver girder
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Seems right

sour junco
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what do i do with the 3x?

gloomy rock
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You did it!

gloomy rock
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You multiply it by (4x+2)

sour junco
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Only took us 4 hours

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WOOOOO

sour junco
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Ughhhh can i just leave it like that for now

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You know i know

gloomy rock
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Alright

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a * (c/b)= (ac/b)

sour junco
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12x^2+6x

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?

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Orrrr?

gloomy rock
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On the numerator

sour junco
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Yayyyyyyyy

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😭

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Prayed for times like this

gloomy rock
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I am very proud of you my friend

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You did it on your own

sour junco
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Couldn't have done it without your help or patience

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THANK YOU YOU'RE THE BEST

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🎉

gloomy rock
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Im happy for you

silver girder
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Astro is the best baguette

sour junco
sour junco
gloomy rock
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And you’re welcome

sour junco
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Smartest cookie in the bunch

gloomy rock
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The thing is.. it’s true that we eat a lot of baguette in France

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Not even a stereotype

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Because it’s a fact

silver girder
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Indeed

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Miam

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Le pain

gloomy rock
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Ouiii

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Alright i think I’ll log off now

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Take care of you guys

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And Eve, good luck for tomorrow

sour junco
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You as well!!!!

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THANK YOU

gloomy rock
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Im sorry that i can’t help you any further

sour junco
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No you helped a lot

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I'm content

gloomy rock
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If they don’t ask you to use chain rule directly then don’t use it. Just use shortcuts like (ln(u))=u’/u

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Or (e^u)’=u’e^u

sour junco
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Ok I will try to memorize

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That

gloomy rock
sour junco
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Yeah oui oui whatever that means

gloomy rock
gloomy rock
sour junco
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Chain rule can suck a fart

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Anyway

gloomy rock
sour junco
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Get your well deserved rest

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See you very soon

gloomy rock
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See you Eve! Take care of you

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I hope for the best

sour junco
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Likewise ☺️

gloomy rock
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See you tomorrow

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I’ll see if i can review some things with you before the exam

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See youuuu

sour junco
silver girder
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You need to sleep

sour junco
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🥹