Inverse function:

Generally speaking, let the range of function y=f(x)(x∈A) be C. If a function g(y) is found to be equal to x everywhere, such a function x = g(y) (y ∈ c) is called function y = f (x) (x ∈). The definition domain and value domain of the inverse function y = f (- 1) (x) are the definition domain and value domain of the function y=f(x) respectively.

Generally speaking, if X and Y correspond to a corresponding relation f(x) and y=f(x), then the inverse function of y=f(x) is x=f? -1(y). The condition for the existence of the inverse function (single-valued function by default) is that the original function must be in one-to-one correspondence (not necessarily in the whole number domain). Note: superscript "? 1 "does not represent a power.

In calculus, f? (n)(x) is used to refer to the n-th differential of f.

A function is said to be invertible if it has an inverse function.

Simply put, y and x are interchanged. For example, the inverse function of y=x+2 first represents x as x=y-2. Just change the positions of x and y, then the inverse function of y=x+2 is y=x-2.