can someone please explain the significance of the second derivative in regards to interpreting the shape of the function graphed? For the function f(x)=(20x^2-20)/(x^3+x^2) I got f'(x) = (-20x^4 + 60x^2 + 40x)/(x^3 + x^2)^2, where i found x=0,2,-1...and a local minimum at x=0 and a local maximum at x=2...Lastly i got f''(x)=(-20x^6+80x^5-60x^4-80x^3-160x^2)/(x^3+x^2)^4...Can anyone confirm these to be right and/or tell me the significance of finding the second derivative and when to find it thanks!!![/img]