Answer:
10.125 feet
Explanation:
h(t) = -2t² + 3t + 9
The maximum height is at the vertex of the parabola. For a parabola ax² + bx + c, the vertex is at x = -b/(2a).
t = -3 / (2×-2)
t = 3/4
h(3/4) = -2(3/4)² + 3(3/4) + 9
h(3/4) = -9/8 + 9/4 + 9
h(3/4) = 81/8
h(3/4) = 10.125 feet