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Powers in Sum

Source: RMO 2018 P2

October 7, 2018
algebra

Problem Statement

Let nn be a natural number. Find all real numbers xx satisfying the equation k=1nkxk1+x2k=n(n+1)4.\sum^n_{k=1}\frac{kx^k}{1+x^{2k}}=\frac{n(n+1)}4.