gwd9

leadership

is n an odd integer?

1) n is divisible by 3

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

the key is B.

用举例法， n=3 2n=6 则n是奇数。 n=6 2n=12 n 有4个因子，而12有8个因子，则n为偶数。

即使加上条件一，仍然不能推出，难道不应该是e么？