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Suppose that a bottle rocket is launched upward with a initial velocity of 96ft/sec from a height of 880ft. Its height is h, in feet, after t seconds is given by h(t)=-16^2 + 96t + 880. After how long will the rocket reach the ground?

 Feb 11, 2021
 #1
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When rocket hits ground , height =0

0 = -16 t+ 96t + 880    Quadratic formula to find t....   throw out negative t value

 Feb 11, 2021
 #2
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-16t^2  +  96t  +  880   =  0        multiply through  by   -1

 

16t^2  -  96t  -  880   =  0       divide through  by  16

 

t^2  - 4t  -   55  =  0                 factor

 

(t  - 11)  ( t + 5)   =  0

 

The first factor set to   0   and solved for t   will  give us  the answer

 

t  - 11   = 0

 

t  =  11   seconds

 

cool cool cool

 Feb 11, 2021

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