Find the intervals where the function is increasing and decreasing for the following function. f(x) = x3 -3x2 -9x Select all the true statements below. O f(x) is increasing on the interval ( - oo, - 1) O f(x) is decreasing on the interval ( - co, - 1) Of(x) is increasing on the interval ( - 1,3) O f(x) is decreasing on the interval ( - 1,3) Of(x) is increasing on the interval (3,co) Of(x) is decreasing on the interval (3, co)