Question

what is an inverse function?

Answer 1

In mathematics, if ƒ is a function from a set A to a set B, then an inverse function for ƒ is a function from B to A, with the property that a round trip (a composition) from A to B to A (or from B to A to B) returns each element of the initial set to itself.

Simplifying that - It means that when you plug x into f(x), you get y, and when you plug y into the inverse of f(x), then you should get x.