>>11090879Your set is:
(X,Y) s.t. 0 < y/x < 3, or 0 < y < 3x.
Intersected with the set 0 < x
And with the set x < (y/x)(3 - y/x).
Since x and y , 3 - y/x are all positive, we can try to do some stuff with that equation, without changing the equality sign. Like x^3 < 3yx - y^2, so we can calculate the boundaries of y using, for example, the quadratic formula. Denote the result as y1(x) and y2(x). Then u have the integral from min(3x,y2) - max(0,y1), with it being 0 if the max is bigger than the min, from 0 to infinity.
