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Mathematics 15 Online
OpenStudy (itiaax):

Differentiation help. *question below*

OpenStudy (itiaax):

Can I have some help on this, please?

OpenStudy (anonymous):

First, find the derivative (you'll need the product rule for this one):\[y=x^n\ln x~~\implies~~\frac{dy}{dx}=\cdots\] Then plug this result into the equation and check if it holds: \[\begin{align*}x(\cdots)&=x^n+ny\\ &=x^n+nx^n\ln x\end{align*}\]

OpenStudy (itiaax):

\[\frac{ dy }{ dx }=nx ^{n-1}lnx + x ^{n-1}\]

OpenStudy (anonymous):

Right, now sub that into the equation and see if you have an identity.

OpenStudy (itiaax):

\[x(nx ^{n-1}lnx + x ^{n-1})\] Hmm, I don't see an identity :s

OpenStudy (anonymous):

\[x\left(\color{red}{nx ^{n-1}lnx + x ^{n-1}}\right)\] Try distributing that black \(x\) to the other terms.

OpenStudy (itiaax):

\[n^{n-1} x^n \ln(x)+x^n\] ?

OpenStudy (anonymous):

Close, that factor of \(n\) is not raised to anything.

OpenStudy (anonymous):

\[nx^n \ln(x)+x^n\] is correct

OpenStudy (itiaax):

Ah, I see

OpenStudy (itiaax):

Hm, how do I proceed from here? @SithsAndGiggles

OpenStudy (xapproachesinfinity):

just realize that x^nlnx=y replace that by y and you get what you want

OpenStudy (itiaax):

Thank you so much!

OpenStudy (itiaax):

Wow :D

OpenStudy (xapproachesinfinity):

welcome!

OpenStudy (xapproachesinfinity):

Math is so much awesome than WOW!

OpenStudy (itiaax):

haha!

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