A batter hits a baseball upward with an initial speed of 96 feet per second. after how many seconds does the ball het the ground

H = rt - 16t² = t (r - 16t)

Here, r = 96 so

h = 96t - 16t² = 16t (6 - t)

h = 0 ⇒ 16t (6 - t) = 0 ⇒ t = 0 or t = 6

The t = 0 solution corresponds to the instant the batter hits the ball. It hits the ground 6 seconds later.