Real quadratic number field

Definition
A real quadratic number field is a number field obtained by extending the field of rational numbers by the squareroot of a positive square-free integer. In other words, it is a field of the form $$\mathbb{Q}[\sqrt{D}]$$ where $$D > 1$$ and $$D$$ is square-free.

Weaker properties

 * Stronger than::Quadratic number field
 * Stronger than::Totally real number field

Opposite properties

 * Imaginary quadratic number field