20 . Which option is correct? Show work please

D Question 20 Determine the open intervals on which the graph of y = -2x* + 8x* + 7x -7 is concave downward or concave upward. concave downward on (- co , co ) concave downward on - co . 3 : concave upward on O 4 concave downward on |~ co . " 7 : concave upward on DO + concave upward on | - co . 2 ; concave downward on 3 . O 4 concave upward on |~ co , 7 7 : concave downward on 3