Question

A ball is launched from 8 feet off the ground at an initial vertical speed of 64 feet per second. It is aimed across a field at a target also 8 feet off the ground. The height of the ball at time, t, in seconds, is given by the function, h = –16t 2 + 64t + 8. It will take the ball a0 seconds to hit its target.

Answer 1

h = –16t 2 + 64t + 8
since both the launch height and target height are identical we can say height is 0
solve for t

0 = -16t^2 + 64t +8

-8(2t^2-8t-1) =0
divide both sides by -8

2t^2-8t -1 = 0

t = 4.12 and -0.121

since it can't be a negative number:

t = 4.12 seconds ( round off as needed)