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题库 / Prep2007E1-DS-38
If r and s are positive integers, is ~$\frac{r}{s}$~ an integer?
(1) Every factor of s is also a factor of r.
(2) Every prime factor of s is also a prime factor of r.
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.
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25=5² 125=5³
B：prime factor不重复，可以是分数
（2）反例 125和25（想只有一个质因子的情况）
(2)s的因子包括1,s,质因子,质因子的不等于s的乘法组合. s的质因子能被r整除，没有考虑s的质因子的乘法组合是否能被r整除。