albinogmat wrote:There is a straight line that passes through two points (-r,-s)(-t, u). Is the slope negative?
(1)-t> -r
(2)u> -s
I went for A. Is that right? Please explain.
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Albi
Slope of a line passing through two points (x1, y1) and (x2, y2) = (y2 - y1)/(x2 - x1)
In this case, slope of the line = [u - (-s)]/[-t - (-r)] = (u + s)/(r - t)
Statement 1: -t > -r implies r - t > 0, but we do not know if u + s is negative or not. It may or may not be negative; NOT sufficient.
Statement 2: u > -s implies u + s > 0, but we do not know if r - t is negative or not. It may or may not be negative; NOT sufficient.
Combining (1) and (2), r - t > 0 and u + s > 0, so slope of the line should also be > 0, which means the slope will be positive; SUFFICIENT.
The correct answer should be
C.
