作者headnobig (Actor)
看板GMAT
标题Re: [计量] GWD11-Q36
时间Mon Oct 6 01:39:57 2008
※ 引述《chilis (庞克新生报到^_^)》之铭言：
: When positive integer x is divided by 5, the remainder is 3; and
: when y is divided by 7, the remainder is 4. When positive integer y
: is divided by 5, the remainder is 3; and when y is divided by 7,
: the remainder is 4. If x > y, which of the following must be a
: factor of x - y?
题目有打错吗?
第2行的y应该是指X吧
如果是的话再继续看 囧
1.X>Y
X = 5*(某数A) + 3
Y = 5*(某数B) + 3
X-Y = 5*(A-B) [(A-B)>0]
=> X为5的倍数
2.X>Y
X = 7*(某数C) + 4
Y = 7*(某数D) + 4
X-7 = 7*(C-D) [(C-D)>0]
=> X为7的倍数
X-Y为正整数>0 又为5和7的倍数, 故必为35的倍数
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