algebra equation

Question

Arianna is going through a ball from the top floor of her middle school. When she throws the ball from 192 feet above the ground the function h(t)=-16^2+48+192

find when the ball hits the ground.

Answer 1

h(t) = -16t^2 + 48t +192 = 0 (0 is ground level, height = 0)

divide by -16 to simplify and get

t^2 -3t - 12 = 0

use the quadratic formula:

t = 3/2 + or - (1/2)sqr(9+48) = about 5.3 seconds to hit the ground