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

1 Answer
Nov 27, 2015

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

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

Explanation:

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

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

Using standard form #(dy)/(dx)=v (du)/dx+u(dv)/(dx)#
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Let #u=2x-1 -> (du)/dx=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#