/sci/ - Science & Math

Is it possible to remove irrationality from denominator in pic rel?
Because it's possible in the case of [math]\dfrac{1}{\sqrt{2}}[/math], [math]\dfrac{1}{1+\sqrt{2}}[/math] and [math]\dfrac{1}{1+\sqrt{2}+\sqrt{3}}[/math]

But with 3 roots it's a lot harder, or maybe even impossible. Is it possible?