请教GWD一道题

huangluyao

If s⁴v³x
⁷ < 0, is svx < 0?
(1)     v < 0

(2)     x > 0

                 

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.

我认为选C，但答案是E.  请高手解答。谢谢！

huangluyao

哦，明白了。谢谢！

jedimin

因为
S可正可负
所以无法确定

lansere

1和2其实是等价的。
S^4* V^3 * X^7 < 0 --> S可为正负，V和X必定异号。
1和2的条件只能推出V和X异号，其实这个结果已经包含在题干中了。剩下S不知道正负，所以推导不出来svx < 0