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        riddles >> medium >> Subtract Exponent Products, Get 1
        
(Message started by: K Sengupta on Jun 25^th, 2008, 8:38am)

Title: Subtract Exponent Products, Get 1
Post by K Sengupta on Jun 25^th, 2008, 8:38am

Determine all possible quadruplet(s) (P, Q, R, S) of nonnegative integers that satisfy this equation:

2^P*3^Q – 5^R*7^S = 1

Title: Re: Subtract Exponent Products, Get 1
Post by Eigenray on Jun 26^th, 2008, 12:31am

I think [link=http://mathworld.wolfram.com/ZsigmondyTheorem.html]this theorem[/link] will help (for some cases; then reduce to those cases).