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Mathematics 24 Online
OpenStudy (anonymous):

Use logarithmic differentiation to find the derivative of the function.

OpenStudy (anonymous):

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

OpenStudy (anonymous):

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

OpenStudy (anonymous):

ok we take the log and get \[\sin(x)\ln(x)\]

OpenStudy (anonymous):

now take the derivative using product rule and get \[\cos(x)\ln(x)+\frac{sin(x)}{x}\]\]now multiply by original function to get the answer: \[x^{\sin(x)}(\cos(x)\ln(x)+\frac{\sin(x)}{x})\]

OpenStudy (anonymous):

this is the answer...

OpenStudy (anonymous):

why do u have to multiply by the original function

OpenStudy (anonymous):

it was wrong!

OpenStudy (anonymous):

really?

OpenStudy (anonymous):

ok first you have to multiply by the original function because step one was to take the log

OpenStudy (anonymous):

\[\frac{d}{dx}\ln(f(x))=\frac{f'(x)}{f(x)}\] so \[f'(x)=f(x)\times \frac{d}{dx}\ln(f(x))\]

OpenStudy (anonymous):

in other words to take the derivative first take the log, then take the derivative, then multiply by the original function

OpenStudy (anonymous):

you have \[y=x^{sin(x)}\]take the log get \[\ln(x^{\sin(x)})=\sin(x)\ln(x)\]so far i think this is right

OpenStudy (anonymous):

now take the derivative of \[\sin(x)\ln(x)\] using product rule. the derivative of sine is cosine, so first term could be \[\cos(x)\ln(x)\] the derivative of \[\ln(x)\] is \[\frac{1}{x}\] so second term is \[\frac{\sin(x)}{x}\] and i think the derivative of that product is \[\cos(x)\ln(x)+\frac{\sin(x)}{x}\]

OpenStudy (anonymous):

what is it supposed to be?

OpenStudy (anonymous):

it is correct they just wanted sin(x)/x b4 cox x ln x

OpenStudy (anonymous):

need help with another

OpenStudy (anonymous):

y=(cox(9x))^x

OpenStudy (anonymous):

ok well as long as the first one was right we can continue, but i think i posted a response to the second one. did you see it?

OpenStudy (anonymous):

y=(cox(9x))^x is this like this... y=(cos(9x))^x

OpenStudy (anonymous):

\[y=(\cos(9x))^{x}\]

OpenStudy (anonymous):

same idea. take the log. simplify using property of log. take the derivative. multiply by original function

OpenStudy (anonymous):

did you check previous post? i think all details are there

OpenStudy (anonymous):

of course they might want you to write \[\frac{9x\sin(9x)}{\cos(9x)}\] as \[9x\tan(9x)\]

OpenStudy (anonymous):

so what is the full answer

OpenStudy (anonymous):

e^9xtan(9x)

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