A projectile is launched into the air. The function h(t) = –16t2 + 32t + 128 h hieght t seconds After how many seconds will the projectile land back on the ground?

Answer 1

The height is 0 when it hits the ground, right?

-16t2 + 32t + 128 = 0

t2 - 2t - 8 = 0

(t - 4)(t + 2) = 0

t - 4 = 0

t = 4 seconds

t + 2 = 0

t = -2

Well, we can't go backward 2 seconds, but this completes the parabola behind the launching point.