Definition:Binomial (Euclidean)/Fifth Binomial/Example

Example
Let $a$ and $b$ be two (strictly) positive real numbers such that $a + b$ is a binomial.

By definition, $a + b$ is a fifth binomial :
 * $(1): \quad b \in \Q$
 * $(2): \quad \dfrac {\sqrt {a^2 - b^2}} a \notin \Q$

where $\Q$ denotes the set of rational numbers.

Let $a = \sqrt {13}$ and $b = 3$.

Then:

Therefore $\sqrt {13} + 3$ is a fifth binomial.