Given the function f (x) = log, take a as the base 1 + X / 1-x (a > 0, a ≠ 1) to find the inverse function

Given the function f (x) = log, take a as the base 1 + X / 1-x (a > 0, a ≠ 1) to find the inverse function

y=(1-a^y)/(1+a^y) (a>0,a≠1)