Answer:
144 ft
Step-by-step explanation:
h(t) = -16t² + 64t + 80
The maximum height is at the vertex. We can find the vertex of a parabola using -b / (2a):
t = -64 / (2×-16)
t = 2
The vertex is at 2 seconds. The height of the stone at this time is:
h(2) = -16(2)² + 64(2) + 80
h(2) = 144
The maximum height is 144 feet.