GMAT考题：OG2017Q-DS-239

GMAT考题

If x is a positive integer, is ~$\sqrt{x}$~ an integer?

(1) ~$\sqrt{4x}$~is an integer.

(2)~$\sqrt{3x}$~ is not an integer

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.

毕出

题目分析：

（1）~$\sqrt{4x}=2\sqrt{x}$~是整数，因为2是整数，~$\sqrt{x}$~必然也是整数。

（2）~$\sqrt{3x}$~不是整数，例如x=1满足条件2，但~$\sqrt{x}$~是整数；又如x=2，满足条件2，~$\sqrt{x}$~不是整数。

因此，本题答案为（A），仅条件1可以解题，条件2不行。

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