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2018 PAMO Shortlist: Diophantine equation

Source: 2018 Pan-African Shortlist - N5

May 6, 2019
number theoryDiophantine equation

Problem Statement

Find all quadruplets (a,b,c,d)(a, b, c, d) of positive integers such that (1+1a)(1+1b)(1+1c)(1+1d)=4. \left( 1 + \frac{1}{a} \right) \left( 1 + \frac{1}{b} \right) \left( 1 + \frac{1}{c} \right) \left( 1 + \frac{1}{d} \right) = 4.