# 2nd derivative trouble

1. Aug 25, 2008

### ande1717

f(x)=x/x^2+1
f'(x)= 1-x^2/(x^2+1)^2
But then I can't seem to work through taking the 2nd derivative, perhaps I am not using the chain rule right.
I get -4x^5-2x^3-2x/(x^2+1)^4