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If x+15 = 19, evaluate x^3-x^2+16x^-1

 

Solver by factoring: x^2 -4x-21=0 The two possible solutions possible are in the form of x=a and x=b. Evaluate a^2+b^2+a+b=

 

Thanks and have a great day! laugh

Guest May 1, 2017
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If x + 15  = 19 , then x  = 4

 

So.....x^3-x^2+16x^-1    evaluates to

 

(4)^3  - (4)^2  + 16/4  =

 

64  - 16  +  4  =

 

52

 

 

 

x^2  - 4x  -  21   = 0    factor

(x - 7) ( x + 3)  = 0

Setting each factor and solving fo x, we have that x  =7  or x  = -3

So  a^2+b^2+a+b  =    7^2 + (-3)^2  + 7  - 3   =   62

 

Thanks to hectictar for catching my error on the second part....!!!!!

 

 

cool cool cool

CPhill  May 1, 2017
edited by CPhill  May 2, 2017

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