SOLUTION: A baseball is hit from a height of 0.8 m. After "t" seconds, its height "h", in metres, is given by the equation h=−5t2+20t+0.8. How long does the ball stay at least 15 m abo

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Question 1006685: A baseball is hit from a height of 0.8 m. After "t" seconds, its height "h", in metres, is given by the equation h=−5t2+20t+0.8. How long does the ball stay at least 15 m above the ground? (5 marks)
Answer by josmiceli(19441)   (Show Source): You can put this solution on YOUR website!

I want to solve for


use quadratic formula









sec
----------------
and, also


sec
-----------------
The difference in these times is the time period
when m

2.154 sec answer
----------------
Here's a plot of the equation:

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