Gah! Inverses!
Step-by-step explanation:
This is a pretty simple concept, just switch the x and f(x) values!
If you don't understand, look at how I solve it!
Switching the positions of the x and f(x) values...
Note: That f(x)^-1 is the proper notation for inverse functions.
There you go!
Hope this helps, and don't procrastinate!