SOLUTION: (this is a word problem involving quadratic equation) an object is projected directly upward from the ground. after t seconds its distance in feet above the ground is s=144t-16r

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Question 347093: (this is a word problem involving quadratic equation)
an object is projected directly upward from the ground. after t seconds its distance in feet above the ground is s=144t-16r^2 after how many sec. will the object be 128 feet above the ground? (please explain how u got the answer and use the factoring method)
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
an object is projected directly upward from the ground. after t seconds its distance in feet above the ground is s=144t-16r^2 after how many sec. will the object be 128 feet above the ground?
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When the object is on the ground, s=zero.
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Solve: -16t^2+144t = 0
-16t(t-9) = 0
t = 0 seconds or t = 9 seconds
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That means the object was on the ground with
time started and is back on the ground after
9 seconds.
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Cheers,
Stan H.