Which of the following describes the set of all possible values of the positive integer k such that, for each positive odd integer n, the value of ~$n \over k$~ is midway between consecutive integers?
All positive integers greater than 2
All prime numbers
All positive even integers
All even prime numbers
All positive even multiples of 5
【引用】
n是一个正奇数,k为正整数,n/k要在两个连续整数的正中间,那就是“X.5”的形式,所以k只能为2,“All even prime numbers”→偶质数就只有2一个,所以答案为D
注意表达: the value of n/k is midway between consecutive integers=值为“x.5",则K一定为2
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