Determine the intervals over which f(x) = -x3+3x is increasing or decreasing. f(x) is decreasing on (-, 0)U(2, ). f(x) is increasing on (0, 2). f(x) is decreasing on (-, -2) U(0, ). O f(x) is increasing on (-2, 0). f(x) is decreasing on (0, 2). O f(x) is increasing on (-, 0)U(2, 0). f(x) is decreasing on (-, -2)U(-2, 0). O f(x) is increasing on (0, ).