扫描二维码，直接登录
题库 / Prep2007E2-DS-21
Is the integer n odd?
(1) n is divisible by 3.
(2) 2n is divisible by twice as many positive integers as n.
Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.
Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.
BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.
EACH statement ALONE is sufficient.
Statements (1) and (2) TOGETHER are NOT sufficient.
还没有题目讲解（毕出老师会陆续发布对官方考题的解读，请保持关注）。
同意tomorrow在杀G的解答。
同时转另一个思路：
1.假设n=x^m * y^n,（x y为质数） 则n的因子数为（m+1）*（n+1）
2.如果2不是n 的因子（即n是奇数），则 2 n 的因子数为（m+1）*（n+1）*（1+1），即是n 的因子数的两倍。
登录 或 注册 后可以参加讨论