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The equation y = -16t^2 + 26t + 105 describes the height (in feet) of a ball tossed up in the air at 26 feet per second from a height of 105 feet above the ground. In how many seconds will the ball hit the ground? Express your answer as a decimal rounded to the nearest tenth.

 Jun 12, 2021

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 #1
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+1

When the ball hits the ground, the height, y, will be zero

 

0 = -16t^2 + 26t + 105       Use the quadratic formula to solve for t ....throw out the negative value....

 Jun 12, 2021
 #2
avatar+129847 
+2

Rewrite  as

 

16t^2   - 26t    -  105   =  0           factor  as

 

(8t  +15)  (2t  -  7)    

 

The second factor  set to  0  and solved for t  gives  us what we need......t   =  7/2 sec  =  3.5 sec

 

 

cool cool cool

 Jun 13, 2021

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