prep-ds 161,201 请教大家（关于ＳＬＯＰＥ）

maomm

161.     16120-!-item-!-187;#058&010949

In the xy-coordinate plane, line m and line k intersect at the point (4, 3).  Is the product of their slopes negative?

 

(1)  The product of the x-intercepts of lines m and k is positive.

 

(2)  The product of the y-intercepts of lines m and k is negative.

(1)知道Y=0,则LINE M和LINE K的X都是0,所以应该就能确定它们斜率的积,(2)知道X=0,则3Y=B, ===即两个斜率乘积为负的.我觉得是D,而答案是C,请问我的思路错了吗?

201.     19278-!-item-!-187;#058&012507

If k is a line in the xy-plane, what is the slope of k ?

 

(1)  The x-intercept of k is 2.

 

(2)  The y-intercept of k is 3.

 

由1可得0=2a+b,则斜率就是0呀.由2可得B=3,为什么答案是B,A错在哪儿呢?

很感谢回复.

maomm

自己帮忙顶一下,特请有空的同学可以帮忙我一下.

很感谢.

maomm

谢谢MM,我就是没有找到第一题的特例来着.

maomm

shaan, thanks for your copious help