求救:有没有好办法?

Numbers 1 through 10 are written on a board. At any time, numbers a, b, c
may be replaced by (2(b + c) − a)/3, (2(c + a) − b)/3, (2(a + b) − c)/3.
Can a number greater than 20 eventually appear on the board?

Thanks

所有跟帖: 

Impossible. -innercool- 给 innercool 发送悄悄话 innercool 的博客首页 (154 bytes) () 10/23/2009 postreply 21:15:26

回复:求救:有没有好办法? -火球魔法- 给 火球魔法 发送悄悄话 火球魔法 的博客首页 (258 bytes) () 10/25/2009 postreply 16:31:37

多谢大侠们不吝指教。 -cma- 给 cma 发送悄悄话 (0 bytes) () 10/26/2009 postreply 08:24:50

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