Homework Help: Differenciate twice or integrate twice?

1. Sep 10, 2010

jinx007

I am confuse a question state f(x) = (ln x )^2 .... i skip a part..

show that f'' (x) = 0 (not concern with the answer but what does f'' means is it that i have to differenciate twice or integrate twice..??)

my second question: how to differenciate y = (ln x )^2

2. Sep 10, 2010

danago

Re: differenciation

It means differentiate twice.

To actually do it, think about using the chain rule...

3. Sep 10, 2010

jinx007

Re: differenciation

chain rule that is dy/dx = dy/dt x dt/dx of course i must apply it

4. Sep 11, 2010

HallsofIvy

Re: differenciation

Yes, and with y = (ln x )^2 , t= ln x so you want (d(t^2)/dt)(d ln(x)dx)