Question

A point (x,y) in the xy-plane whose coordinates satisfy xy<0 lies in quadrant(s) ____ or ____ .

Answer 1

The possible ordered pairs whose product will be negative (less than zero) are,


$(x,-y) \: or \: (-x,y)$

That is all these products will give us,

$- xy$

$-xy< 0$

The point must be in the second quadrant where x is negative and y is positive.


Or in the fourth quadrant, where y is negative and x is positive.