Identify the open intervals on which the graph of the function is concave upward or concave downward. Assume that the graph extends past what is shown. 10- 8- 6- 4- 10 8.-6 -4 20 2 -2- -4- -6- -8- Note: Use the letter U for union. To enter , type infinity. 4 4 B Enter your answers to the nearest integer. If the function is never concave upward or concave downward, enter NA in the associated response area. concave upward: concave downward: