Find the intervals on which the graph of f is concave upward. the intervals on which the graph off is concave downward. and the inection points. f(x)= -x4 +28x3-23x+ 19 For what interval(s) of x is the graph of f concave upward? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. a; :1- A. (Type your answer in interval notation. Type an exact answer. Use a comma to separate answers as needed.) i: B. The graph is never concave upward. For what interval(s) of x is the graph of f concave downward? Select the correct choice below and, if necessary, fill in the answer box to complete your choice. uzj i1~ A. (Type your answer in interval notation. Type an exact answer. Use a comma to separate answers as needed.) If} B. The graph is never concave downward. Determine the x coordinates of any inection points of the graph of f(x). Select the correct choice below and, if necessary, fill in the answer box to complete your choice. .;j'j;. A. x = (Type an exact answer. Use a comma to separate answers as needed.) .;j'j;. B. There are no inection points. The marketing research department of a computer company used a large city to test market the firm's new laptop. The department found the relationship between price p (dollars per unit) and the demand x (units per week) was given approximately by the following equation. P = 1836 - 0.17x 0