1 6 Relations and Functions Objectives Identify the

1 -6 Relations and Functions Objectives Identify the domain and range of relations and functions. Determine whether a relation is a function. Vocabulary Words Relation and Function Vertical Line Test Domain and Range Holt Algebra 2

1 -6 Relations and Functions A relation is a pairing of input values with output values. It can be shown as a set of ordered pairs (x, y), where x is an input and y is an output. The set of input (x) values for a relation is called the domain, and the set of output (y) values is called the range. Holt Algebra 2

1 -6 Relations and Functions Mapping Diagram Domain Range A 2 B C Set of Ordered Pairs {(2, A), (2, B), (2, C)} (x, y) Holt Algebra 2 (domain, range)

1 -6 Relations and Functions Example 1: Identifying Domain and Range Give the domain and range for this relation: {(100, 5), (120, 5), (140, 6), (160, 6), (180, 12)}. List the set of ordered pairs: {(100, 5), (120, 5), (140, 6), (160, 6), (180, 12)} Domain: {100, 120, 140, 160, 180} The set of x-coordinates. Range: {5, 6, 12} Holt Algebra 2 The set of y-coordinates.

1 -6 Relations and Functions Example 2 Give the domain and range for the relation shown in the graph. List the set of ordered pairs: {(– 2, 2), (– 1, 1), (0, 0), (1, – 1), (2, – 2), (3, – 3)} Domain: {– 2, – 1, 0, 1, 2, 3} The set of x-coordinates. Range: {– 3, – 2, – 1, 0, 1, 2} Holt Algebra 2 The set of y-coordinates.

1 -6 Relations and Functions Not a function: The relationship from number to letter is not a function because the domain value 2 is mapped to the range values A, B, and C. Function: The relationship from letter to number is a function because each letter in the domain is mapped to only one number in the range. Both functions and non-functions are relations! Holt Algebra 2

1 -6 Relations and Functions Holt Algebra 2

1 -6 Relations and Functions Example 3 A: Using the Vertical-Line Test Use the vertical-line test to determine whether the relation is a function. If not, identify two points a vertical line would pass through. This is a function. Any vertical line would pass through only one point on the graph. Holt Algebra 2

1 -6 Relations and Functions Example 3 B Using the Vertical-Line Test Use the vertical-line test to determine whether the relation is a function. If not, identify two points a vertical line would pass through. This is a function. Any vertical line would pass through only one point on the graph. Holt Algebra 2

1 -6 Relations and Functions Example 3 C: Using the Vertical-Line Test Use the vertical-line test to determine whether the relation is a function. If not, identify two points a vertical line would pass through. This is not a function. A vertical line at x = 1 would pass through (1, 1) and (1, – 2). Holt Algebra 2

1 -6 Relations and Functions Function: The relationship is a function if each member of the domain is mapped to only one number in the range. Example 4 A: Is this relation a function? From graph or ordered pairs: {(– 2, 2), (– 1, 1), (0, 0), (1, – 1), (2, – 2), (3, – 3)} Holt Algebra 2

1 -6 Relations and Functions Function: The relationship is a function if each member of the domain is mapped to only one number in the range. Example 4 B: Is this relation a function? {(100, 5), (120, 5), (140, 6), (160, 6), (180, 12)}. Identify the domain and range: Domain: {100, 120, 140, 160, 180} Range: {5, 6, 12} Holt Algebra 2

1 -6 Relations and Functions Example 4 C: Is this relation a function? A. There is only one price for each shoe size. The relation from shoe sizes to price makes is a function. B. Names in a classroom and grades C. (Reverse B…) from class grades, find student name. Holt Algebra 2

1 -6 Relations and Functions Example 5 A: Is this relation a function? Use the vertical-line test to determine whether the relation is a function. If not, identify two points a vertical line would pass through. This is not a function. A vertical line at x = 1 would pass through (1, 2) and (1, – 2). Holt Algebra 2

1 -6 Relations and Functions Example 5 B: Is this relation a function? Use the vertical-line test to determine whether the relation is a function. If not, identify two points a vertical line would pass through. not a function Holt Algebra 2