GWD-最新试题2－M－Q22

litaowan4455

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!

alice2292

A

kjhggsdf

B

X^3<-9

X<-3条件2充分

litaowan4455

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。

micklefuer

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

呵呵，我刚起来的说

kjhggsdf

A对.

偶没有看到 x is negative这个条件.粗心了.

xihonghui

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?