Editing Division by zero (section)

===Extended real line===
The [[affinely extended real numbers]] are obtained from the [[real number]]s <math>\R</math> by adding two new numbers <math>+\infty</math> and <math>-\infty,</math> read as "positive infinity" and "negative infinity" respectively, and representing [[point at infinity|points at infinity]]. With the addition of <math>\pm \infty,</math> the concept of a "limit at infinity" can be made to work like a finite limit. When dealing with both positive and negative extended real numbers, the expression <math>1/0</math> is usually left undefined. However, in contexts where only non-negative values are considered, it is often convenient to define <math>1/0 = +\infty</math>.