Answer:
See below in bold.
Step-by-step explanation:
a) h = -3t^2 + 15t = 0
-3t(t - 5) = 0
t = 0, 5 are the zeroes of the relation.
b) The ball hits the ground when h = 0 so it is after 5 seconds.
c) The path of the ball is a parabola which opens downwards so the maximum height is when x = 5/2 = at 2.5 seconds.
d) this maximum height is -3(2.5)^2 + 15(2.5) = 18.75 meters.