If the function f:[1,∞)→[1,∞) is defined by f(x)=2x(x−1), then f−1(x) is

If the function f:[1,∞)→[1,∞) is defined by f(x)=2x(x−1), then

1.	If the function f:[1,∞)→[1,∞) is defined by f(x)=2x(x−1), then f−1(x) is
Answer» If the function $f : [1, \infty) \to [1, \infty)$ is defined by $f (x) = 2^{x (x - 1)}$ , then $f^{- 1} (x)$ is