SOLUTION: if a ball is thrown vertically up from the ground, its height h after t seconds is given by h(t)=96t-16t^2 A. how long does it take the ball to return the ground. B. how long doe

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Question 931460: if a ball is thrown vertically up from the ground, its height h after t seconds is given by h(t)=96t-16t^2
A. how long does it take the ball to return the ground.
B. how long does it take the ball to pass through a height of 80ft on the way back down>
Found 2 solutions by Alan3354, stanbon:
Answer by Alan3354(69443) About Me  (Show Source):
You can put this solution on YOUR website!
if a ball is thrown vertically up from the ground, its height h after t seconds is given by h(t)=96t-16t^2
A. how long does it take the ball to return the ground.
96t-16t^2 = 0
Solve for t.
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B. how long does it take the ball to pass through a height of 80ft on the way back down>
96t-16t^2 = 80
Solve for t.

Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
if a ball is thrown vertically up from the ground, its height h after t seconds is given by h(t)=96t-16t^2
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A. how long does it take the ball to return the ground.
Solve::
96t-16t^2 = 0
16t(6 - t) = 0
Positive solution:
t = 6 seconds
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B. how long does it take the ball to pass through a height of 80ft on the way
Solve::
96t-16t^2 = 80
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16t^2 - 96t + 80 = 0
16(t^2 - 6t + 5) = 0
Factor::
16(t-5)(t-1)
On the way up:: t = 1 second
On the way down:: t = 5 seconds
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Ans: 5-1 = 4 seconds
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Cheers,
Stan H.
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