Question

The height h in feet, of a rocket t seconds after blast-off is given by the formula h(t) = 1440t - 16t^2

After how many seconds will the rocket hit the ground?

Answer 1

90 seconds

Explanation:

The rocket will hit the ground when h(t) = 0. This can be solved by solving the equation 0 = 1440t - 16t², which can be rearranged to 0 = 16t² - 1440t. Factoring this equation yields 0 = (16t - 90)(t + 90). This equation has two solutions, t = 90 or t = -90. Since a rocket cannot be in the air for a negative amount of time, the rocket will hit the ground after 90 seconds.