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The equation \(y=-16t^2+28t+144\) describes the height y (in feet) at time t (in seconds) of a ball tossed up in the air at 28 feet per second from a height of 144 feet from the ground. In how many seconds will the ball hit the ground?

 
 Jan 24, 2023
 #1
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Plugging in different values of t, you can find that t = 5.5 works.

 
 Jan 24, 2023
 #2
avatar+454 
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Sorry; I just tried that and its incorrect!

 
 Jan 24, 2023
 #3
avatar+118203 
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\(0=-15t^2+28t+144\\ t=\frac{-28\pm\sqrt{784+8640}}{-30}\\ t=\frac{-28\pm\sqrt{9424}}{-30}\\ t=\frac{+28+4\sqrt{589}}{30}\\ t\approx 4.17 sec\)

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 Jan 25, 2023

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