SOLUTION: A pebble is hurdled upward from the top of a 1120-foot-tall building with an initial velocity of 144 feet per second. Neglecting air resistance, the height h(t) in feet of the pebb

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Question 602466: A pebble is hurdled upward from the top of a 1120-foot-tall building with an initial velocity of 144 feet per second. Neglecting air resistance, the height h(t) in feet of the pebble after t seconds is given by the polynomial function:
h(t)=-16t squared + 144t + 1120
When will the pebble hit the ground?
Answer by stanbon(75887) About Me  (Show Source):
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A pebble is hurled upward from the top of a 1120-foot-tall building with an initial velocity of 144 feet per second. Neglecting air resistance, the height h(t) in feet of the pebble after t seconds is given by the polynomial function:
h(t)=-16t squared + 144t + 1120
When will the pebble hit the ground?
Ans: When h(t) = 0
Solve: -16t^2+144t+1120 = 0
Factor:
-16(t^2-9t-70) = 0
----
t^2-9t-70 = 0
Factor:
(t-14)(t+5) = 0
Ans: time = 14 seconds
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Cheers,
Stan H.
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