SOLUTION: The inital height a ball is thrown in the air is 80 feet, velocity 64 ft. per sec. and g is 32 feet/sec squared. I am supposed to figure out when it will hit the ground in 2 diff

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Question 255611: The inital height a ball is thrown in the air is 80 feet, velocity 64 ft. per sec. and g is 32 feet/sec squared. I am supposed to figure out when it will hit the ground in 2 different ways.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
The initial height a ball is thrown in the air is 80 feet, velocity 64 ft. per sec. and g is 32 feet/sec squared. I am supposed to figure out when it will hit the ground in 2 different ways.
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h(t) = -16t^2 + vot + so
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The height is zero when the ball hits the ground:
Solve -16t^2+64t+80 = 0
Divide thru be -16 to get:
t^2 - 4t -5 = 0
Factor:
(t-5)(t+1) = 0
Positive solution:
t = 5 seconds
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Graph the equations to see when the ball hits the ground:
graph%28400%2C300%2C-10%2C10%2C-10%2C140%2C-16x%5E2%2B64x%2B80%29
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Cheers,
Stan H.