ISL 2012 N6

Let $x$ and $y$ be positive integers. If $x^{2^{n}}-1$ is divisible by $2^{n} y+1$ for every positive integer $n$ , prove that $x=1$ .

Official text Transcription from NuminaMath olympiads, checked word for word against the official paper. Quoted with source.

Solutions

Official solution Solution 1 by the IMO Problem Selection Committee

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