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Mathematics 12 Online
OpenStudy (anonymous):

dy/dx =

OpenStudy (anonymous):

\[y=x^{\log_4(x)}\]

OpenStudy (anonymous):

Take the derivative with respect to x.

OpenStudy (anonymous):

lny = lnx^log_4x

OpenStudy (zzr0ck3r):

\(ln(y)=log_4(x)ln(x)\)

OpenStudy (anonymous):

lny = (log_4x)(lnx)

OpenStudy (zzr0ck3r):

correct

OpenStudy (anonymous):

then how do i derive logs with base log 4?

OpenStudy (anonymous):

is it still 1/x?

OpenStudy (zzr0ck3r):

\((\log_a(x))'=\frac{1}{xln(a)}\)

OpenStudy (anonymous):

wait is it logx/log4 = logx - log4?

OpenStudy (zzr0ck3r):

no

OpenStudy (zzr0ck3r):

log(a/b) = ...

OpenStudy (anonymous):

ahh yeah

OpenStudy (zzr0ck3r):

\(\frac{1}{xln(4)}\)

OpenStudy (anonymous):

so 1/xlog4

OpenStudy (zzr0ck3r):

correct

OpenStudy (anonymous):

i see then use the product rule and multiply by y

OpenStudy (zzr0ck3r):

yep

OpenStudy (anonymous):

thanks ;)

OpenStudy (zzr0ck3r):

chain rule on the left...

OpenStudy (anonymous):

?

OpenStudy (zzr0ck3r):

I get \(x^{\log_4(x)}[\frac{ln(x)+ln(4)\log_4(x)}{xln(4)}]\)

OpenStudy (zzr0ck3r):

\(ln(y)=\log_4(x)ln(x)\) then we take the derivative of both sides \(\frac{1}{y}\frac{dy}{dx}=\frac{1}{xln(4)}ln(x)+\frac{1}{x}\log_4(x)\\\) so \(\frac{dy}{dx}=y(\frac{ln(x)}{xln(4)}+\frac{\log_4(x)}{x})\) now plug in for y \(\frac{dy}{dx}=x^{\log_4(x)}(\frac{ln(x)}{xln(4)}+\frac{\log_4(x)}{x})\)

OpenStudy (zzr0ck3r):

I think

OpenStudy (anonymous):

hmmm

OpenStudy (anonymous):

oh i see it

OpenStudy (zzr0ck3r):

http://www.wolframalpha.com/input/?i=%282x^%28log%28x%29%2Flog%284%29-1%29log%28x%29%29%2Flog%284%29%3D+x^ {\log_4%28x%29}%28\frac{ln%28x%29}{xln%284%29}%2B\frac{\log_4%28x%29}{x}%29

OpenStudy (zzr0ck3r):

the one on the left is the answer the wolfram gives for the derivative, and the one on the right is the answer I gave

OpenStudy (anonymous):

holy toledo, this is intense

OpenStudy (zzr0ck3r):

got to love wolframalpha:)

OpenStudy (anonymous):

after that i had to convert to natural logs, yeah haha my homework is online so i have to get everything PERFECT for it to accept the answer, lol

OpenStudy (anonymous):

but i got it :p

OpenStudy (zzr0ck3r):

:)

OpenStudy (zzr0ck3r):

good question:)

OpenStudy (anonymous):

thanks haha

OpenStudy (zzr0ck3r):

you do good in math?

OpenStudy (anonymous):

yeah I'm taking my 2nd of 4 calculus courses

OpenStudy (zzr0ck3r):

I had a feeling....you seem like you got it.

OpenStudy (anonymous):

gonna be a genius when I'm done!

OpenStudy (zzr0ck3r):

think about a math minor, it will look good....

OpenStudy (anonymous):

im gonna major, or at least try

OpenStudy (zzr0ck3r):

oh sweet

OpenStudy (zzr0ck3r):

nm then... you will be fine

OpenStudy (anonymous):

:D

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