Often, to locate a point on a plane, we use two rational numbers in a certain order. We call these numbers **ordered pair**. Examples:

Like this:

We indicate by ( |

**Comments:**

1) In general, being *x *and *y* any two rational numbers we have: . Examples:

2) Two ordered pairs (*x*, *y*) and (*r*, *s*) are equal only if *x* = *r* and *y *= *s*.

## Graphical representation of an ordered pair

We can represent a pair ordered by a point in a plane. This point is called the **Image** of the ordered pair.