Question

The height h of an arrow in feet is modeled by h(t) = -16t^2 + 63t +4, where t is the time in seconds since the arrow was shot. How long was the arrow in the air?

Answer 1

If the arrow is in the air, then when it hits the ground, h(t)=0. So:
0=-16t²+63t+4
16t²-63t-4=0
(16t+1)(t-4)=0
t= -1/16 or 4
Using the positive result of 4, we get t=4 seconds as the time the arrow was in the air
☺☺☺☺