vmalaiya wrote:

Guys I need help with this one...

In the xy-plane, the line k passes through the origin and through the point (a, b), where ab is not equal to 0. Is b positive ?

1. The slope of line k is negative.

2. a < b

We know ab><0 => (a,b) is not on neither of the axes.

(1) slope of k is (-) => (a,b) in 2nd or 4th cuadrant. Insuf => B, C or E.

(2) if a<b, (a,b) could be in the 1st, 2nd or 3rd cuadrant. Insuf => C or E.

(1&2) We intersect {2nd c, 4th c} and {1st c, 2nd c, 3rd c} and arrive at a single solution: (a,b) is on the 2nd cuadrant => b IS positive. C.