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标题: 一道DS题 [打印本页]

作者: zengjie0140    时间: 2002-10-15 13:47     标题: 一道DS题

一道DS题:
if x and y are positive integers and x is a multiple of y, is y=2?
  (1)y不等于1
  (2)x+2 is a multiple of y
答案是C,为什么我觉得答案应该是E?
作者: zyh79    时间: 2002-10-15 14:03

x=k1*y,(x+2)=k2*y
==> 2=y*(k2-k1)
k2-k1为positive integer,y为positive integer
因为y不等于1,y只有等于2




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