Suppose the function f(x) has a domain of all real numbers except x = −4 . the first derivative of f(x) is shown below. f '(x) = 2(x − 3)e8x (x + 4)7 find the interval(s) where f(x) is increasing. (enter your answers using interval notation. if an answer does not exist, enter dne.) (3,∞) incorrect: your answer is incorrect. find the interval(s) where f(x) is decreasing. (enter your answers using interval notation. if an answer does not exist, enter dne.) (−∞,3) incorrect: your answer is incorrect.