Question 864333: A firecracker is fired straight up into the air out of a window of a building. Its height, in feet, is given by h = -16 t^2 + 112 t + 304, where t is the time, in seconds, the fircracker has been in the air.
By setting up and solving an equation, find the time(s) when it reaches a height of 400 feet
Answer by lwsshak3(11628)   (Show Source):
You can put this solution on YOUR website! A firecracker is fired straight up into the air out of a window of a building. Its height, in feet, is given by h = -16 t^2 + 112 t + 304, where t is the time, in seconds, the fircracker has been in the air.
By setting up and solving an equation, find the time(s) when it reaches a height of 400 feet
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h = -16 t^2 + 112 t + 304
400=-16 t^2 + 112 t + 304
-16 t^2 + 112 t -96=0
16 t^2 - 112 t +96=0
t^2-7t +6=0
(t-6)(t-1)=0
t=6
and
t=1
After 1 sec firecracker reaches height of 400 ft on the way up.
After 6 sec fire cracker falls to a height of 400 ft on the way down.
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