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Help.

NotSoSmart  Jan 4, 2018
 #1
avatar+87294 
+1

13.....

 

y  =  - 16x^2 +  95x + 10 

 

The x value that maximizes the height is given by   -95/ 2(-16)   =  -95/-32  =  95/32

 

So....subbing this back into the function, we can find the max height  =

 

-16 (95/32)^2  + 95(95/32)  + 10  =  151.02 ft

 

It will hit the ground when

 

-16x^2  + 95x  +  10  =  0

 

-95 ±√ [ 95^2  -  4(-16)(10) ]

--------------------------------------

               2(-16)

 

 

-95 ±√ 9665

__________       =    [ take the negative root]

       -32

 

-95  -  98.3

__________         =    6.04 sec

     -32

 

 

 

14.....this parabola turns upward so we can eliminate the first two answers

 

Using   (2, 15)   ....the  last  equation  gives

 

4(2)^2  - 3(2)  +  5

 

16  -  6  +  5

 

10 +  5  =   15

 

So.....the last answer is correct

 

 

cool cool cool

CPhill  Jan 4, 2018

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