Data Sufficiency
试题详情
题目：
If k and ℓ are lines in the xy-plane, is the slope of k less than the slope of ℓ ?
- The x-intercept of line k is positive, and the x-intercept of line ℓ is negative.
- Lines k and ℓ intersect on the positive y-axis.
选项:
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.
答案:
C
提问：
能明白单独条件1或条件2是不足的
但是对于条件1和2联合起来的解答有疑问。
解答里只画了，途中l1和k相交的情况（l1斜率大于k斜率，这点没有问题）；我在解答时还画了l2和k相交的情况。
我认为l2满足题目要求，和x轴焦点为负，和k线交点的y值>0。但此时l2和k相交，l2和k的斜率均为负数，且l2斜率小于k斜率，所以我最终选择了E。
不知道我的第二种l2和k相交的情况哪里想错了。[img=/resource/2020-07/22077-1595131528.jpeg]
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