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Indian Mathematical Olympiad 1990 - Problem 2

Source:

August 16, 2009
calculusintegrationquadraticsnumber theory proposednumber theoryDiophantine equation

Problem Statement

Determine all non-negative integral pairs (x,y) (x, y) for which (xy \minus{} 7)^2 \equal{} x^2 \plus{} y^2.