According to the definition of the inverse function, given a function f
[tex]\begin{gathered} f(f^{-1}(x))=x \\ f^{-1}(f(x))=x \end{gathered}[/tex]
Therefore, regardless of function f(x), f(f^-1(x))=x, we do not even need to know the analytic form of f^-1(x). The answer is x.
