Question

For the function f(x)=8(x+10), find f^-1(x)

Answer 1

In other words, find the inverse of the given function f(x).

1.  Replace f(x) with "y."     y = 8(x+10)
2.  Interchange x and y:      x = 8(y+10)
3.  Solve this for y:             y+10 = x/8, or y = x/8 - 10

                                   -1
4.  Replace "y" with "f     (x) "       

          -1           x-80
         f   (x) = ----------     (Answer)
                            8