__Relations__

## Definition

A *relation* is any set of ordered pairs.

### Domain

The *domain* is the set of all first elements. These "first elements" are referred to as the *independent variable*, or X.

example: (0,0), (8,9), (5,5), (4,2)

The domain of the set is {0, 4, 5, 8}

### Range

The *range* is the set of all second elements. These "second elements" are referred to as the *dependent variable*, or Y.

example: (0,0), (8,9), (5,5), (4,2)

The range of the set is {0, 2, 5, 9}

### Visual Display

The data in the set can be displayed visually. The two types of visual presentations are *mapping diagrams* (left) and *graphs* (right).

example: (0,0), (8,9), (5,5), (4,2)

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This information is taken from the chapter **Functions 1** in the **IB Mathematical Studies** textbook.