SOLUTION: The height, h, in metres, of an infield ball t seconds after being hit is given by the formula: h=20t-5t^2. How long is the ball in the air?

Algebra ->  Algebra  -> Quadratic Equations and Parabolas -> SOLUTION: The height, h, in metres, of an infield ball t seconds after being hit is given by the formula: h=20t-5t^2. How long is the ball in the air?      Log On

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Question 1499: The height, h, in metres, of an infield ball t seconds after being hit is given by the formula: h=20t-5t^2. How long is the ball in the air?
Answer by khwang(438) About Me  (Show Source):
You can put this solution on YOUR website!
Suppose the ball reached the ground finally.
Solve h(t)=20t-5t^2 = 5t(4-t) = 0,
We have t = 4 or t =0(means initial)
Answer: 4 sec later the ball reached the ground and so it
stayed in the air for 4 seconds.