Problem List Next Problem (1 point) Let f(x) = (5x + 8)2. At what x-values is f'(x) zero or undefined? x = (If there is more than one such x-value, enter a comma-separated list; if there are no such x-values, enter "none".) On what interval(s) is f(x) increasing? f (x) is increasing for x in (If there is more than one such interval, separate them with "U". If there is no such interval, enter "none".) On what interval(s) is f(x) decreasing? f(x) is decreasing for x in (If there is more than one such interval, separate them with "U". If there is no such interval, enter "none".) Note: You can earn partial credit on this