SOLUTION: A baseball player hits a ball into the air. The ball's height above the ground, in meters, t seconds after being hit, is approximated by h(t)=1+13t-5t^2. Algebraically determine th

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Question 171386: A baseball player hits a ball into the air. The ball's height above the ground, in meters, t seconds after being hit, is approximated by h(t)=1+13t-5t^2. Algebraically determine the time when the ball first reaches a height of 9 m.
Answer by solver91311(24713) About Me  (Show Source):
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You want to find the value of t when h(t)=9

So set the expression for h(t) equal to 9 and solve for t.

1%2B13t-5t%5E2=9

Put it in standard form:

-5t%5E2%2B13t-8=0

Factors to %28x-1%29%28-5x%2B8%29=0, so t=1 or t=8%2F5. But the question asks for when the ball will FIRST be at 9 meters, so pick the lowest time value, namely t=1