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- Sun Apr 11, 2021 11:31 pm
- Forum: National Math Olympiad (BdMO)
- Topic: BDMO Secondary National 2021 #2
- Replies: 2
- Views: 3341
Re: BDMO Secondary National 2021 #2
I have a different approach to this. After your 4th line, we can do as follows: 2 a +2 b =1+ ab or, 2( a + b )=1+ ab Here, L.H.S. is even. So R.H.S. should also be even. That is possible only if a and b both are odd. So let's assume, a =2 p -1 and b =2 q -1 where p and q and positive integers. So we...