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TOT 360 1993 Spring O J3 (a -b) perfect square if ab/(a-b)=c

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June 10, 2024
number theoryPerfect SquarediophantineDiophantine equation

Problem Statement

Positive integers aa, bb and cc are positive integers with greatest common divisor equal to 11 (i.e. they have no common divisors greater than 11), and abab=c\frac{ab}{a-b}=c Prove that aba -b is a perfect square.
(SL Berlov)