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题库 / Prep2008E1-DS-3
How many different prime numbers are factors of the positive integer n ?
(1) Four different prime numbers are factors of 2n.
(2) Four different prime numbers are factors of n2.
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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1-2n到n， 2有可能是n也有的质因子，也可能不是，2n有4个，n就可能是3个或4个；不唯一，不充分；
2-n平方到n，降低质因子的次方项，不能减少质因子的个数， n方有4个，则n也有4个；充分
选B
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