The Extended Real Numbers

Definition: The Extended Real Numbers

The extended real numbers are the union of the real numbers with the set containing the symbols $-\infty$ and $+\infty$:

$$\mathbb{R}\cup \{-\infty ,+\infty \}$$

NOTATION

$$\overline{\mathbb{R}}[-\infty ;+\infty ]\mathbb{R}\cup \{-\infty ,+\infty \}$$

Operations