olymmath

ISL 2015 N2

    Let aa and bb be positive integers such that a!ba!b ! is a multiple of a!+b!a!+b!. Prove that 3a⩾2b+23 a \geqslant 2 b+2. (United Kingdom)

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

    Official text: IMO 2015 Shortlist booklet, page 8.

    Solutions

    Official solution Solution 1 by the IMO Problem Selection Committee

    The terms of the source let olymmath link to this solution but not copy it. Read the solution (IMO official site).

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