Every rational number can be represented by an irreducible fraction with a nonnegative denominator.
For expressions involving integers, the four basic operations of arithmetic and square roots, you can still factor out squares from square roots, and rationalize the denominators.
But, while exploring biquadratic equations and their solutions, i encountered two expressions for the same number, for instance :
$\frac{\sqrt{5-2\sqrt{2}}+\sqrt{5+2\sqrt{2}}}{2}$ and $\frac{\sqrt{10+2\sqrt{17}}}{2}$
Both have only one fraction line, no squares inside the square root symbols. So, is there a way to write such expressions with a unique canonical closed form ?