Russian 1996

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Problem 20

Do there exist three integers each greater than one such that the square of each less one is divisible by both the others?

 

Answer

No.

 

Solution

Take x > y > z. Then x divides y2 - 1, so x and y are coprime. Both divide z2-1, so their product xy must divide z2 - 1. But xy > z2 > z2-1. Contradiction.

Thanks to Suat Namli

 


 

Russian 1996

© John Scholes
jscholes@kalva.demon.co.uk
12 January 2004
Last corrected/updatd 12 Jan 04