What are the first and second derivatives of f(x)=ln(x^(2x+1) ) f(x)=ln(x2x+1)?

1 Answer
Nov 27, 2015

First derivative: (dy)/(dx) =2ln(x)-1/x+2dydx=2ln(x)1x+2

2nd derivative: 2/x + 1/(x^2)2x+1x2 Did not have time to do the (d^2)/dxd2dx properly so just gave the answer!

Explanation:

Given: y=ln(x^(2x+1))y=ln(x2x+1)

Write as : y=(2x-1)ln(x)y=(2x1)ln(x)

Using standard form (dy)/(dx)=v (du)/dx+u(dv)/(dx)dydx=vdudx+udvdx
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Let u=2x-1 -> (du)/dx=2u=2x1dudx=2
Let v=ln(x) ->color(white)(...) (dv)/dx = 1/x

Then (dy)/(dx) = ln(x)(2)+(2x-1)(1/x)

(dy)/(dx) = 2ln(x)+(2x)/x-1/x

(dy)/(dx) =2ln(x)-1/x+2