l 3 Find the open intervals on which the iiJnction f (z) = 249: (s + 7] is concave upwaro or concave downward. Note: USE the letter U TOT union. To enter DO, tvpe innitv. If the function is never concave upward or concave dowmward, enter NA in the associated response area. concave upward: l D concave downward: l D 1 Find the pointts} of inection of the function f (z) = 242 3 (z + '3']. Enter the exact answers in increasing order of the mcoordinate. If there are less than two points of inflection, enter mm the remaining response areas