Answer:
Explanation:
If h is the height of the ball off the ground, if we want to find the time, t, when the ball hits the ground again, we set h equal to 0, because the height of something when it is on the ground is 0.
and solve for the values of t. Begin by factoring out a -t:

By the Zero Product Property, either -t = 0 or t - 4 = 0. We already know that at time 0 the ball hit the ground for the first time because that was given in the problem. That means that the ball hit the ground for the second time 4 seconds later.