SOLUTION: At time t = 0 a slingshot fires an egg straight up from a window of a tall building. The height of the egg above ground as a function of time is given by y = -4.9t2 + 21t + 5

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Question 632872: At time t = 0 a slingshot fires an egg straight up from a window of a tall building. The height of the egg above ground as a function of time is given by
y = -4.9t2 + 21t + 56, where y is in meters and t is in seconds. a. How high up is the window? b. How high is the egg after 3 s? c. After launching the egg, how long does the shooter have to wait to see the egg go by the window on the way down? d. At what times is the egg 65 m above ground? (Solve with the quadratic formula; then check your work using the trace feature of a graphing calculator.) e. When does the egg impact the ground?
I began by drawing a picture of an egg being slung out of a window. I figured that vf=0, the distance from the ground to the window was 56, acceleration was negative leaving the constant -9.8m/s^2. I plugged this information into the equation +vf%5E2-v0%5E2=2%28a%28change+in+x%29%29+ but my answer was clearly wrong and I cannot figure out how else to go about this question.
Answer by stanbon(75887) About Me  (Show Source):
You can put this solution on YOUR website!
At time t = 0 a slingshot fires an egg straight up from a window of a tall building. The height of the egg above ground as a function of time is given by
y = -4.9t2 + 21t + 56, where y is in meters and t is in seconds.
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a. How high up is the window?::: 56 meters
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b. How high is the egg after 3 s? find f(3)
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c After launching the egg, how long does the shooter have to wait to see the egg go by the window on the way down?:: Solve f(t) = 56
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d. At what times is the egg 65 m above ground? (Solve with the quadratic formula; then check your work using the trace feature of a graphing calculator.)
Or solve for f(t) = 65
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e. When does the egg impact the ground?:: Solve f(t) = 0
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Cheers,
Stan H.
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