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Differing Ratio Expression Exercise (Posted on 2024-08-29) Difficulty: 3 of 5
Determine all possible real values of x, that satisfy this equation:
(x2+x)3    (x-3)3
------- - ------- =1
(x2+3)3   (x2+3)3

No Solution Yet Submitted by K Sengupta    
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Solution Solution Comment 1 of 1
Denominators are the same

x^6 + 3x^5 + 3x^4 + x^3 - x^3 + 9x^2 - 27x + 27 =  x^6 + 9x^4 + 27x^2 + 27

3x^5 - 6x^4 - 18x^2 - 27x  =  0
x^5 - 2x^4 - 6x^2 - 9x  =  0
From summing coefficients of even vs odd powers, we see that x = -1 is a solution

x^5 + x^4  -  3x^4 - 3x^3 + 3x^3 + 3x^2  -  9x^2 - 9x  =  0
(x)(x+1)(x^3 - 3x^2 + 3x - 9)  =  0    x=3 also works
(x)(x+1)(x-3)(x^2 + 3) = 0

Real solutions:  {-1, 0, 3} which all check and this was the requested information.

Complex solutions: {√3i, -√3i} (but I did not check to see if these solve the original equation)

  Posted by Larry on 2024-08-29 09:14:51
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