inverse function

Function that exactly reverses the transformation produced by a function f; it is usually written as f−1. For example, to find the inverse of a function y = 3x + 2, x is made the subject of the equation: 3x = y − 2, so x = (y − 2)/3. So 3x + 2 and (x − 2)/3 are mutually inverse functions. Multiplication and division are inverse operations (see reciprocals).

An inverse function is clearly demonstrated on a calculator by entering any number, pressing x2, then pressing √x to get the inverse. The functions on a scientific calculator can be inversed in a similar way.