SOLUTION: A firecracker is fired straight up into the air out of a window of a building. Its height, in meters, is given by h = -5 t^2 + 15 t + 100, where t is the time, in seconds, the firc
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Question 864482: A firecracker is fired straight up into the air out of a window of a building. Its height, in meters, is given by h = -5 t^2 + 15 t + 100, 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 10 meters Answer by LinnW(1048) (Show Source):
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Set h = 10
add -10 to each side
multiply by -1
divide by 5
factor
Possible values for t are 6 and -3
So the firecracker has been in the air 6 seconds.
