Maybe I am wrong. An Counterexample.

来源: wxcfan123 于 2012-03-11 12:04:18 [] [旧帖] [给我悄悄话] 阅读数 : 0 (304 bytes)
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回答: 有没有好办法？ 由 cma 于 2012-03-10 19:31:33

Consider the solution of quadratic equation x^2 + 4xy + y^2 = c. x, y are integers iff
3y^2 + c is a square. If c does not have factor 3, or is a square, it is impossible. Easy to find counterexample:

x = 13 (1, 2), y = 22 (1, 3) and x^2 + 4xy + y^2 = 286 has no interger solution.

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• 回复：Maybe I am wrong. An Counterexample. -cma- ♂ 给 cma 发送悄悄话 (163 bytes) () 03/11/2012 postreply 13:04:23

• ＨＩ，Ｘ＝１９，Ｙ＝－１。 -jinjing- ♀ 给 jinjing 发送悄悄话 (0 bytes) () 03/11/2012 postreply 15:30:43

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