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SqueezeMethod UK Intermediate

Problem - 2241

Solve in positive integers (1+1x)(1+1y)(1+1z)=2


By symmetry, let's assume xyz. Then we have (1+1z)3(1+1x)(1+1y)(1+1z)=2 This implies z3. Do casework:

  • (1) z=1_ This implies (1+1x)(1+1y)=1. This cannot hold because (1+1x)>1 and (1+1y)>1 means (1+1x)(1+1y)>1.
  • (2) z=2_ This implies (1+1x)(1+1y)=43. Because xy, therefore (1+1y)2(1+1x)(1+1y)=432y6 Setting y=2,3,4,5, and 6, respectively, finds (x,y,z)=(15,4,2),(9,5,2) are solutions.
  • (3) z=3_ This implies (1+1x)(1+1y)=32. By a similar reasoning, we have (1+1y)2(1+1x)(1+1y)=323y4 Setting y=3 and 4 respectively finding (x,y,z)=(8,3,3) and (5,4,3) are solutions.

Therefore, the solutions are all the permutations of (7,6,2),(9,5,2),(15,4,2),(8,3,3),(5,4,3).

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