Functions that aren't invertible can be made invertible by restricting their domains. For example, the function x^2 is invertible if we restrict x to the interval [0, infty), or to any subset of that interval. In that case, the inverse function is sqrt (x). (We could also restrict x^2 to the domain (-infty, 0] , in which case the inverse function would be - sqrt (x).
Similarly, by restricting the domain of the function f(x) = 2x^2 - 4x - 5 to an interval, we can make it invertible. What is the largest such interval that includes the point x = 0?
