Maths Olympiad Prep

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, 2024

Number theory Difficulty 5.0 AIME, harder Prove it United States

Problem:

Determine, with proof, whether there exist positive integers xx and yy such that x+yx+y, x2+y2x^{2}+y^{2}, and x3+y3x^{3}+y^{3} are all perfect squares.

Solution

Solution:

Take (x,y)=(184,345)(x, y) = (184, 345). Then x+y=232x+y = 23^{2}, x2+y2=3912x^{2}+y^{2} = 391^{2}, and x3+y3=68772x^{3}+y^{3} = 6877^{2}.

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Source: MathNet, licensed CC-BY-4.0. Statement reproduced verbatim; metadata (topic, difficulty) added by this project.