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题库 / Prep2007E2-DS-65
If ab ≠ 0 and points (-a, b) and (-b, a) are in the same quadrant of the xy-plane, is point (-x, y) in this same quadrant?
(1) xy > 0
(2) ax > 0
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.
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题干可知，ab 为同正同负。第二或第四象限。
1）只能推出x、y同正同负，第二或第四。不行
2）没有 Y 的条件。
1+2可知，a,x,y 同正同负，因此可确定 肯定和题干的点在一个象限，不管她是第二还是第四。
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