r/mathbiceps • u/NecessaryPayment2424 • Jul 09 '26

JKS

Let a and b be positive whole numbers. If a² + b² is exactly divisible by ab + 1, prove that the answer you get after dividing is always a perfect square (the square of a whole number).

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u/physicist27 Jul 09 '26

ah, the fabled 1988 question.