SOLUTION: A toy rocket is shot vertically upward from the ground. Its distance in feet from the ground in t seconds is given by s(t)=-16(t^2)+142t. At what time(s) will the ball be 172 ft fr
Question 166879: A toy rocket is shot vertically upward from the ground. Its distance in feet from the ground in t seconds is given by s(t)=-16(t^2)+142t. At what time(s) will the ball be 172 ft from the ground? Answer by nerdybill(7384) (Show Source):
You can put this solution on YOUR website! s(t)=-16(t^2)+142t
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In this case, they are saying that if s(t) equals 172 feet what is t?
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Simply set s(t) to 172 and solve for 't':
s(t)=-16(t^2)+142t
172=-16(t^2)+142t
16(t^2)-142t+172=0
8(t^2)-71t+86=0
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Since it is difficult to factor, we use the quadratic equation.
Doing so will yield:
x = {7.428, 1.447}
Units are in seconds
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Here's the quadratic equation:
