题库搜索>问题求解PS-13693
If a and b are positive integers such that a – b and a/b are both even integers, which of the following must be an odd integer?
分析A选项
分析B选项
分析C选项
分析D选项
分析E选项
a-b为偶数---->a、b同奇同偶
a/b为偶数---->a一定为偶数
所以a、b一定为偶数
因为a=b*偶数
所以a一定是4的倍数
A a/2一定是偶数
B b/2 可奇可偶
C (a+b)/2 可奇可偶
D (a+2)/2=a/2+1 一定是奇数
E (b+2)/2=b/2+1 可奇可偶
所以选D
662352yo
不是说a,b一定是偶数吗?推荐解析里面的BC选项分析是不是写错了啊?b/2应该是偶数把?(a+b)/2也是偶数?
626617yh
a-b=2k; a/b=2n; (b+2k)/b=2n b是偶数 代入就得答案了
Kath1230
这里不是说b也是偶数吗?为什么(b+2)/2不是奇数呢?
月冷隐回复Kath1230
b=2和b=4,结果不同的。
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2019-06-15 15:42:07
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