Suppose that a bottle rocket is launched upward with a initial velocity of 96ft/sec from a height of 880ft. Its height is h, in feet, after t seconds is given by h(t)=-16^2 + 96t + 880. After how long will the rocket reach the ground?
When it hits the ground, the height = 0 ......so......
-16t^2 + 96t + 880 = 0 divide through by -16
t^2 - 6t - 55 = 0
(t - 11) (t + 4) = 0
The first factor set = 0 gives us what we want
t - 11 = 0
t = 11 sec to hit the ground