Question

Gianna is going to throw a ball from the top floor of her middle school. when she throws the ball from 32 ft above the ground, the function h(t)=-16t^2 +48t+32 models the height, h, of the ball above the ground as a function of time, t. at what time will the ball reach a height of 64 ft?

Answer 1

height = 32 ft

h(t) = -16t^2 + 48t + 32

h = 64 ft

height = 64 - 32 = 32 because she is 32 ft up the floor

32 = -16t^2 + 48t + 32

Solve for t

16t^2 - 48t - 32 + 32 = 0

Simplify

16t^2 - 48t = 0

Factor

16t (t - 3) = 0

Solve for t

16 t = 0 t - 3 = 0

t = 0/16 t = 3

t = 0

time can not be 0, so the answer is time = 4

the other is zero