४ -12-11-10-9 -8 -7-6-5-4-3-2-1,0 2 3 4 5 -7- -8- -9- -10- -11- -12- -13- -14- -15- the vertex on the graph point) (5, 0); (- 5, 0); (0, - 5); x = - 8