Inverse
The inverse of the one-to-one function f is the function f -1 defined by the following correspondence: f -1(x) = y if and only if f(y) = x. The domain of f -1 is equal to the range of f, while the range of f -1 is equal to the domain of f.
Notice that f ( f -1(x) ) = x for all x in the domain of f -1 and f -1( f(x) ) = x for all x in the domain of f.