GWD-13-32

liushuixian

Q32:

If xyz ≠ 0, is x (y + z) ≥ 0?

(1)   │y + z│ = │y│ + │z│

(2)     │x + y│ = │x│ + │y│

                  

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.

讨论的答案是C。

但是，因为xyz ≠ 0，综合条件1，2只能得出 x (y + z) 大于 0而不等于，我的倾向是这条应该选E，因为没办法得出她等于0。

open to discuss

sportman

题目问的是充分性，而不是必要性。

所以只要能推出x(y+z)>0，那么也就满足了x(y+z)>=0