Answer: time = 20 seconds
Step-by-step explanation:
h(t) = -16t² + 316t + 80
The shape of this graph is an upside parabola ∩.
It lands on the ground when height (h) = 0
Set the equation equal to zero, factor, and solve for t.
0 = -16t² + 316t + 80
0 = 4t² - 79t - 20 divided both sides by -4
0 = (4t + 1)(t - 20) factored the equation
t = -1/4 t = 20 Applied Zero Product Property and solved for t
Since we know time cannot be negative, disregard t = -1/4
The only valid solution is: t = 20
