Answer:
D
Step-by-step explanation:
D is a function because it passes the vertical line test, meaning that you can draw a vertical line anywhere through the graph and it will only it the lines one time.
If the ball hit the ground it means that its height is equal to 0. In order to find the time after the ball <span>will hit the ground, we need to find the solution of the equation h(x)=0 which is different to 0.
-4.9x^2+21.3x=0
x(-4.9x+21.3)=0
-4.9x+21.3=0
x=21.3/4.9 = 4.3469 seconds</span>
Technically, this counts
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