Your Ex,5should be 5^2m,3 ...3^2n...,We get |9781-Z^2|=1,

In generail,If we get |9781(M1)^2-(N1)^2|=1,M1 can divided by 2,...continue,at last we get |9781(Mk)^2-(Nk)^2|=1, Mk can't be divided by 2,contradiction,so,.....>1.

I can't copy here and busy,If you want to know more,let me know.I can tell you detail or correct my "blind act" later.

Some answer in web is wrong for P.

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• 回复：Your Ex,5should be 5^2m,3 ...3^2n...,We get |9781-Z^2|=1, -calligraphy- ♂ (425 bytes) () 01/27/2011 postreply 11:26:44

• 回复：回复：Your Ex,5should be 5^2m,3 ...3^2n...,We get |9781-Z^2|=1, -jinjing- ♀ (438 bytes) () 01/27/2011 postreply 17:19:24