Question

Given `f(x)= x^3 +2x -1`, how do you find `1/ [f^(-1)(2)]`?

Answer 1

`1/f^(-1)(2) = 1`

Explanation:

If `f(x) = 2` then we have:

`x^3+2x-1 = 2`

and so:

`0 = x^3+2x-3 = (x-1)(x^2+x+3) = (x-1)((x+1/2)^2+11/4)`

So the only Real root is `x = 1` and we find:

`1/f^(-1)(2) = 1/1 = 1`