Thread: Inverse functions

Hi, I gotta show that f(x)=4x^3/(x^2+1) has an inverse and find f(-1)' (2)

I cant seem to find y, and f(-1)(x). After I find that I guess I derivate and put in the derivate=2, but I need some help to get started off

I don't know how to do it... but it seems very complicated

http://www.wolframalpha.com/input/?i=x+%3D+\dfrac{4y^3}{y^2+%2B+1}

Especially is this part:

Originally Posted by fredrikhoeg

Hi, I gotta show that f(x)=4x^3/(x^2+1) has an inverse and find f(-1)' (2) I cant seem to find y, and f(-1)(x). After I find that I guess I derivate and put in the derivate=2, but I need some help to get started off

One does not need the exact inverse.