回複：四位平方數，前兩位和後兩位都相同，怎麽求？（知道是7744，但怎麽推呢？

Some times,"logic guess" is best.
11^2=121,so,121*x^2=aabb,x^2=81 is not good ,64 is OK.
121*64=7744.

所有跟帖： 

• good for a few guesses; but not for a lot guesses. -皆兄弟也- ♂ (0 bytes) () 06/17/2010 postreply 01:14:11

• Yes,we can cancel 81,49,36,25,16 by number theory. -jinjing- ♀ (0 bytes) () 06/17/2010 postreply 16:13:58