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>
I guess this how it would go
<span><span><span>(5)</span><span>(<span>−2</span>)</span></span>−<span><span>(2)</span><span>(<span>−3</span>)</span></span></span>
So your answer should be <span>−4</span>
First one is -6 and the second one is -3