A toy rocket is launched vertically upward from ground level. This is represented as f(t) = -16t^2 + 128t where t is the time in second and f(t) is the height of the rocket in feet. When will the rocket hit the ground?
divide both sides by -16
0 = -16t^2 + 128t
0 = t^2 - 8t
0 = t(t-8t)
0 = t
0 = t-8
add 8 to both sides
8 = t
the rocket will hit the ground in 8 seconds.
can you tell me if I'm correct?