(1) Negative slope means it goes from top left to bottom right, so all of the points will be in the (-,+) quadrant or the (+,-) quadrant. b could be positive or negative, insufficient.molsen wrote:In the xy-plane, the line k passes through the origin and through the point (a,b), where ab does not equal zero. Is b positive?
(1) The slope of line k is negative
(2) a<b
Answer: C
(2) If a < b, the point could be (4,8) or (-5,-3). b could be positive or negative, insufficient.
(1) & (2) From (1), we know that either a is negative aned be is positive or vice-versa. If we also know that a is less than b, we can eliminate all of the (+,-) options, leaving us in the top left quadrant, in which every point is (-,+). Therefore b is definitely positive and, combined, the statements are sufficient: choose (C).
