The inverse of a function is not always defined. In order for a function
to have an inverse, it must be one to one. A function is said to be
one to one if f(a) = f(b) implies that a = b. In other words, there is
only one value of x that is mapped to each value of y. The inverse of
a function, f is usually denoted 
. Note that if the point
(x,y) is on the function f then the point (y,x) is on the function
. The inverse function can be found by writing y = f(x),
swapping x for y to get x = f(y) and solving for 
.