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The equation y = -16t^2 + 28t + 180 describes the height (in feet) of a ball tossed up in the air at 28 feet per second from a height of 180 feet from the ground. In how many seconds will the ball hit the ground?

 Jul 23, 2021
 #1
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+1

When it hits  the ground  y  = 0

 

So

 

-16t^2  + 28t  + 180   =  0       divide  through by  -4

 

4t^2  - 7t  - 45   =  0

 

Using the Quadratic Formula

 

t  =   7  +  sqrt  [ 7^2  - 4 * 4 * -45 ]                    7  +  sqrt 769

       __________________________  =         _____________   ≈   4.34  sec

                    2 * 4                                                        8

 

 

cool cool cool

 Jul 23, 2021

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