作者chenemily (天天保持好心情)
看板GMAT
标题[问题] pp1-ds 159
时间Mon Nov 9 20:11:43 2009
If n is a positive integer and r is the remainder when (n - 1)(n + 1) is
divided by 24, what is the value of r ?
(1) n is not divisible by 2.
(2) n is not divisible by 3.
请问一下 为何2个一起考虑就可以
所以答案C
谢
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1F：推 musiclife729:连续两个偶数 必为2跟4的倍数 连续三个整数必有一个 11/09 22:35
2F：→ musiclife729:为3的倍数 证明就用代数方式 2K,2K+2,3K+-1去看 11/09 22:36