/0.06 Points] DETAILS Refer to the graph of f shown in the following figure. 5 - 4- 3+ A . X (a) Find the intervals where fis concave upward and the intervals where f is concave downward. (Enter your answers using interval notation.) concave upward concave downward (b) Find the inflection points of f. (Order your answers from smallest to largest x. If an answer does not exist, enter DNE.) ( x, V ) = ( x, y ) = ( x, y ) = ( x, y) =