GMAT考题：OG2017Q-DS-281

GMAT考题

If xy = -6, what is the value of xy(x + y) ?

(1) x - y = 5

(2)~$xy^2 = 18$~

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）根据条件1得x=5+y，代入题目中的xy=-6得到(5+y)y=-6，解得y=1或者y=-6，但无法判断y=1还是y=-6，也就无法计算xy(x + y)的值，所以条件1不满足要求。

（2）~$xy^2=18$~ ，将xy=-6代入解得y=-3，x=2，所以xy(x+y)=6。题目得解。

因此，本题答案为（B），仅条件2可以解题，条件1不行。

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