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What is the sum of the x-values of that satisfy the equation 5 = (x^3 - x^2 - 8x)/(x + 2)?

 Apr 30, 2021
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5 = (x^3 - x^2 - 8x)/(x + 2)    multiply  both sides by  x + 2

 

5 (x + 2)  =  x^3  -x^2  -  8x

 

5x + 10  = x^3  - x^2  -8x        rearrange  as

 

x^3 - x^2  - 13x  -  10  =   0

 

We  have the form    ax^3  + bx^2  + cx + d

 

By  Vieta....the  sum of  the roots   =   -b /a  =  -(-1) / 1   =    1  

 

 

cool cool cool

 May 1, 2021

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