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标题: GWD-最新试题2-M-Q22 [打印本页]

作者: blueshandys    时间: 2007-3-26 07:16     标题: GWD-最新试题2-M-Q22

Q22:

If x is negative, is x < -3?

(1) x2 > 9

(2) x3 < -9

A. Statement (1) ALONE is sufficient, but statement (2) alone is not sufficient.

B. Statement (2) ALONE is sufficient, but statement (1) alone is not sufficient.

C. BOTH statements TOGETHER are sufficient, but NEITHER statement ALONE is sufficient.

D. EACH statement ALONE is sufficient.

E. Statements (1) and (2) TOGETHER are NOT sufficient.

Answer: Thanks!


作者: uspresident    时间: 2007-3-26 13:03

B

X^3<-9

X<-3条件2充分


作者: blueshandys    时间: 2007-3-27 13:00

谢谢!!!

不过偶的想法不同,偶选A。

由(1)推出 x<-3 或者 x>3,由于题目说 x是负数,所以 x < -3,(1)充分。

由 (2) 推出 x < - 3 2/3,由于 -3 2/3 > -3,所以不能推出 x < -3,所以(2)不充分。


作者: sweatfly    时间: 2007-3-27 19:15

Q22:

If x is negative, is x < -3?

(1) x2 > 9

(2) x3 < -9

1) x^2 > 9, then |x| > 3 => x < -3 if x < 0, x > 3 if x > 0, since we already know x < 0, then x < -3, thus 1) by itself is sufficient

2) x^3 < -9, x < -(9)^(1/3), since 3 > 9^(1/3) => -3 < -9^(1/3), x < -9^(1/3) is not sufficient to establish that x < -3, thus 2) by itself is not sufficient

Therefore, the answer is A


作者: uspresident    时间: 2007-3-30 20:27

A对.

偶没有看到 x is negative这个条件.粗心了.


作者: blueshandys    时间: 2007-4-2 12:57

谢谢确认!


作者: gmatplayers    时间: 2007-4-3 13:14

还有一种解法:

(2) x3 < -9

(-3)3=-27

既然 x3 < -9,那么可能x3<-27,也可能-27<x3<-9

所以无法确定x < -3?


作者: alexmingzhu    时间: 2007-4-8 07:43

ding !!!!!!!!!!!!!






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