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Solve the equation, indicate any extraneous solutions.

(2x)/(x^2-1)= (4x^2+6x-6)/(x^3+x^2-x-1) - (1)/(x+1)

 Aug 23, 2016
 #1
avatar+129838 
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(2x)/(x^2-1)= (4x^2+6x-6)/(x^3+x^2-x-1) - (1)/(x+1)  simplify

 

[2x] / [ (x + 1) (x - 1) ]  =  [ 2 (2x^2 + 3x -  3)] / [ x^2 ( x + 1) - 1 (x + 1)] - (1) /(x + 1)

 

[2x] / [ (x + 1) (x - 1) ]  =  [ 2 (2x^2 + 3x -  3)] / [ (x^2 - 1) (x + 1)] - (1) / ( x + 1)

 

[2x] / [ (x + 1) (x - 1) ]  =  [ 2 (2x^2 + 3x -  3)] / [ (x - 1) (x + 1) (x + 1)] - (1) / ( x + 1)

 

Multiply through by the common denominator of (x - 1) (x + 1) (x + 1)

 

2x (x + 1)   = [2 (2x^2 + 3x - 3 ) ]  -  [(x - 1) (x + 1) ]    simplify

 

2x ^2 + 2x   = (4x ^2 + 6x - 6)  - [x^2 - 1) ]

 

2x^2 + 2x  = 3x^2 + 6x - 5

 

x^2 + 4x - 5   = 0     factor

 

(x + 5) (x - 1)   =  0      set both factors to 0

 

x + 5  = 0    →   x = -5   is one possible solution

 

x - 1  = 0  →    x = 1   is another possible solution

 

However........we must reject the second solution because it causes two of the denominators in the original problem to = 0 

 

So.......the only solution is    x  = -5

 

 

 

cool cool cool

 Aug 23, 2016
 #2
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0

Is (x+1) (x+1) (x-1) the least common denominator?? Cant I just multiply everything by (x+1) ?

 Aug 23, 2016
 #3
avatar+12530 
+5


greeting Omi 67laugh

 Aug 23, 2016

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