Explain how long it will take a ball to hit the ground that has been thrown up into the air using this equation: h=-t^2+8t

Answer 1

Set h(t)=0 and solve for t.

-t² + 8t = 0

t(8 - t) = 0

t = 0 or 8

Since t=0 is the moment of launch, the answer must be t=8 sec.