(e) Give the intervals of concavity of f (x). Note: Use the letter U for union. To enter oo, type infinity with a lower case i. If the function is never concave upward or concave downward, enter NA in the associated response area. concave upward: concave downward: (f) Give the inflection points of f (x). Enter your answers in increasing order of the @-coordinate. If there are less than two points of inflection, enter NA in the remaining response areas. Include a multiplication sign between symbols. For example, a . IT