DefinitionFrom an inverse perspective, it take the result and the function to return back to the original input. If a function f(x) has a inverse function f−1(y) then f(f−1(y))=y and f−1(f(x)) = x. Inverse functions are used for solving equations, modeling, and for understanding the relation of variables. We achieve them by solving y=f(x) in regard to y for x, example: f(x)=2x+3 then f−1(y)=2y−3. Hence If f(x)=y then f−1(y)=x, such that f(f−1(y))=y and f−1(f(x))=x.