Is xy > 0?\(xy>0\) means that x and y must have the same sign, so point (x, y) must be either in the first or the third quadrant (green regions).
(1) x-y > -2 --> \(y<x+2\) --> the area below blue line (\(y=x+2\)). (x, y) may or may not be in green region. Not sufficient.
(2) x-2y < -6 --> \(y>\frac{x}{2}+3\) --> the area above red line (\(y>\frac{x}{2}+3\)). (x, y) may or may not be in green region. Not sufficient.
(1)+(2) Below blue line and above red line, is yellow region, which is entirely in I quadrant (where \(y>4\) and \(x>2\)) --> \(xy>0\). Sufficient.
Answer: C.
Hope it helps.
I did get it right in my practice exam (1:34) and I plugged in numbers as couple of the solutions show in this discussion. But I typically do not feel confident mostly because I don't want to keep spending time to cross check / revise. What should I do? What is a recommended method to save time and also inadvertently cross check solution for inequality question types? I don't think I have "problem" with the concept and if I have more time, I do these questions well. Thank you.