Question

A ball is thrown upward with an initial velocity of 48 ft/s from a height 864 ft. h = -16t +48t +864 After how many seconds will the ball reach the ground? (i.e. For what positive value of t is h=0?) ...?

Answer 1

0 = -16 t^2 + 48t + 864 (Divide all by 16)

-t^2 + 3t + 54

(t-9) (t+6) = 0

t = 9s
t = -6s

so the positive value would be : 9s

hope this helps