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(x+y)/(x-y)+(x-y)/(x+y)=1999 (VI Soros Olympiad 1990-00 R1 8.2)

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May 27, 2024
algebra

Problem Statement

Real numbersx x and yy it is know that x+yxy+xyx+y=1999\frac{x+y}{x-y}+\frac{x-y}{x+y}= 1999. Find the value of the expression x4+y4x4y4+x4y4x4+y4.\frac{x^4+y^4}{x^4-y^4}+\frac{x^4-y^4}{x^4+y^4}.