\(\frac{1}{x+1} + \frac{2}{x^3 - x^2 - x + 1} = \frac{3}{1 - x^2}\)

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15. \(\frac{1}{x+1} + \frac{2}{x^3 - x^2 - x + 1} = \frac{3}{1 - x^2}\)

16. \(\frac{x-1}{x-3} - \frac{2x+5}{4} = 1 - \frac{x^2 + 2x - 3}{4}\)

17. \(\frac{x^2 + 2x + 1}{x^2 + 2x + 2} = \frac{7}{x^2 + 2x + 3}\)

18. \(\frac{1}{4x^2 - 12x + 9} - \frac{3}{9 - 4x^2} = \frac{4}{4x^2 + 12x + 9}\)