Going Against Math Rules!

You know how the number one rule for square roots is the fact that $\sqrt{x} + \sqrt{y} \neq \sqrt{x+y}$?

Well, I got bored, so I tried to find a set of numbers where this actually true!

Not sure if it's possible, but yeah, I couldn't find any?

So, do you guys know a set of numbers that satsifies the unsatisfiable? 

Thanks!