co-ordinate - gmatprep

[arocks]

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

1) The product of the x-intercepts of lines l and k is positive
2) The product of the y-intercepts of lines l and k is negative

Pls explain. Thanks.


OA - C[/spoiler]

[camitava]

arocks,
Slop = y-intercept/ x-intercept
say y-intercept of l and k be y1 and y2
x-intercept of l and k be x1 and x2

So m1 * m2 = (y1 * y2) / (x1 * x2)

So to find out whether m1 * m2 < 0, we have to know the fact whether both (x1 * x2) and (y1 * y2) are < 0 or not. So C is the answer to chose.

[arocks]

Thanks.