1. The problem statement, all variables and given/known data f(x)=x/x^2+1 Find horiz. asymptotes and use them w/ concavity and intervals to sketch the curve 2. Relevant equations 3. The attempt at a solutionf'(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 But thats not right... please help!