Relations and Functions

Chapter 5, Section 2Algebra 1

What is a Relation?

• A relation is a set of ordered pairs.

DOMAIN

• The domain of a relation is the set of the first coordinate of the ordered pair.

• In the function, f(x) = x+22, the domain is all real numbers.

RANGE

• The range is the set of all the second coordinates of a function.

• In the function f(x) = |x|, the range is the set of all nonnegative numbers.

Finding Domain and Range

Age (years) Height (meters)18 4.2520 4.4021 5.2514 518 4.85

Giraffes

Find the domain and the range of the data above.

Ordered Pairs

• List the information as ordered pairs

(18, 4.25)(20, 4.40)(21, 5.25)(14, 5.00)(18, 4.85)

Domain: {14, 18, 20, 21}Range: {4.25, 4.40, 4.85,

5.00, 5.25}

Age (years) Height (meters)

18 4.25

20 4.40

21 5.25

14 5.00

18 4.85

Example 1

• Find the domain and range of the relation represented by the data in the table.