GWD 有关因子的问题

carolcai

Is the integer n odd?

(1)     n is divisible by 3.

(2)     2n is divisible by twice as many positive integers as n.

                  

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

又是老管的题目，这个怎么分析啊，答案是B

ted810

条件2的意思是，2n能整除的数的数量是n的2倍。

因为2n比n只多了2一个因子，但是达到了能整除的数的数量是原来的2倍，那么就是原来所有能整除的数乘以2与原来不重复。这就是说原来因子中不能2。

所以条件2可以推出m为奇数。

carolcai

哦，这样啊。多谢