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标题: 数学勾勾362和80题类似，到底选什么啊 [打印本页]
作者: chantelle 时间: 2009-11-15 18:12
标题: 数学勾勾362和80题类似，到底选什么啊
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1) km=偶数
2) k+m=奇数
解答：设k=m*n,则k/m=n,即要确定n是否为偶数.由(1)得,m^2*n=偶数,但是只要其中一个为偶数即可,无法确定n是否为偶数;由(2)得,m(n+1)=奇数,则m与n+1需要同时为奇数,则可得n为偶数
答案:B
362、k是m的因子，问m/k是偶数？ 1、mk是偶数；2，m+k是奇数
条件一，mk为偶数，情况一m和k有一偶，k为m 的因子，进而推得，k为奇，m为偶，m/k中必存在因子2，则可以判断；情况二，都为偶，结果必定为偶。
条件二 可推得m和k必有一偶，同上述情况一
故选D
作者: chantelle 时间: 2009-11-15 18:12
怎么编辑去掉这些乱码啊
作者: financelse 时间: 2009-11-15 18:24
选B
作者: davion 时间: 2009-11-15 18:29
选B
作者: sayysong 时间: 2009-11-15 18:30
赞成 B。
12/4=3可以把条件1给推翻掉
作者: foxdee 时间: 2009-11-15 18:36
答案是B，因为若K和M都是偶数，也有K=M的特例，除后结果是1不是偶数
这种DS题只要举特例就很好排除
作者: chantelle 时间: 2009-11-15 18:37
谢谢了
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