A( x ) = 2 + : 2 - 18x + 4. Over which of these domains could you define f-1(x)? Remember that f(x) must be one-to-one (only one y value for each x value) over the domain where f" (x) is defined as a function. So, in some cases you must restrict the domain of f(x) so that it's one-to-one. There might be more than one section of domain that's one-to-one. HINT: The function f(x) is one-to-one wherever it's monotonic ("monotonic" simply means increasing or decreasing over the entire interval, so the derivative does not change sign). To find these intervals, start by taking the first derivative, which is f' (a) = 3x2 + 3x - 18, and setting it equal to zero. 1. (-00, -3] 11. [-3, 00) Ill. [2, 00)