An inverse function is a function that will “undo” anything that the original function does. For example, if a function takes <em>a</em> to <em>b</em>, then the inverse must take <em>b</em> to <em>a</em>.
These are the conditions for two functions and to be inverses:
for all in the domain of
for all in the domain of
This is because if and are inverses, composing and (in either order) creates the function that for every input returns that input. This is known as “the identity function".
We know that and are inverse functions and according with the above information we get that: