Using the derivative of f(x) given below, determine the intervals on which f(x) is increasing or decreasing. f'(x) = x 1/3(x-8) O Increasing on (0, ) O Decreasing on (0, 8); increasing on (8,) O Decreasing on (-, 0) U (8, ); increasing on (0, 8) Decreasing on (0, 8); increasing on (-0, 0) U (8,)