Your best submission for each question part is used for your score. 1. [-/1 Points] DETAILS Math 110 Course Resources - Curve Sketching Course Packet on intervals of concavity Suppose the second derivative of f is given by f"(x) - 8(x + 9) Determine the intervals of concavity of f. (36 -x2)5 Enter your answer using interval notation. If an answer does not exist, enter DNE. f is concave up on f is concave down on