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

##### 1 Answer

Oct 9, 2016

#### Explanation:

If

#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

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