quadratic question

Question

If a ball is thrown upward from the ground with an initial speed of 112 feet per second, its height h, in feet, after t seconds is
h = −16t2 + 112t.
How many seconds will it take for the ball to fall back to the ground?

sec

Answer 1

h = -16t² + 112t

0 = -16t² + 112t

0 = -16t(t - 7)

t - 7 = 0

t = 7 seconds