Definition:Square Root/Positive

Definition
Let $x \in \R_{> 0}$ be a (strictly) positive real number.

The positive square root of $x$ is the number defined as:
 * $+ \sqrt x := y \in \R_{>0}: y^2 = x$

Also known as
The positive square root is sometimes also referred to as the principal square root, but it is usually preferred that this terminology be reserved for square roots of a complex number.

When $\sqrt x$ is written, then by convention this refers to the positive square root of $x$.

Also see

 * Definition:Negative Square Root