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[tex] \frac{1}{a - b} + \frac{1}{a - b} + \frac{2a}{a {}^{2} + b {}^{2} } + \frac{4 {a}^{3} }{a {}^{4} + b { }^{4} } = \frac{8 {a}^{7} }{ {a}^{8} - {b}^{8} } [/tex]
[tex] \frac{1}{a - b} + \frac{1}{a - b} + \frac{2a}{a {}^{2} + b {}^{2} } + \frac{4 {a}^{3} }{a {}^{4} + b { }^{4} } = \frac{8 {a}^{7} }{ {a}^{8} - {b}^{8} } [/tex]