Question

http://prntscr.com/3wqzum

Answer 1

So far, I've noticed that \(\frac{x}{y}\) should be positive for the condition to hold true.

Answer 2

The same for \(\frac{y}{x}\) of course.

Answer 3

\[1 + \dfrac{1}{xy^2} + \dfrac{1}{x^2y} + \dfrac{1}{x^3y^3}\]Not sure if writing the expression like that would help, but why not.

Answer 4

@dan815