Question

A girl stands on the edge of her dorm roof and throws a ball into the air. The​ ball's height above the ground after t seconds is given by h equals negative 16 t squared plus 64 t plus 80h=−16t2+64t+80. When will the ball hit the​ ground?

Answer 1

find t when h=0.

If you divide through by -16, then just solve

t^2 - 4t - 5 = 0