A boy standing on a 64-foot cliff drops a coin off the cliff. If the equation of the height, h, of the coin, t, seconds after it drops is h = -16t2 + 64, about how many seconds will the coin take to reach the bottom of the cliff?
A. 1 second
B. 1.5 seconds
C. 2 seconds
D. 2.5 seconds

Question

A boy standing on a 64-foot cliff drops a coin off the cliff. If the equation of the height, h, of the coin, t, seconds after it drops is h = -16t2 + 64, about how many seconds will the coin take to reach the bottom of the cliff?
	A.	1 second
	B.	1.5 seconds
	C.	2 seconds
	D.	2.5 seconds

anonymous · Answer

factor -16t^2+64

-16(t-2)(t+2)

t=-2, t=2

C.

anonymous · Answer

We know that the coin did not travel back in time.

$$t \neq -2,$$
$$t =2$$