1. Relations and Functions
Lesson 2-1
Relations and Functions

2. Relation – set of pairs of input and output values.
You can write a relation as a set of ordered pairs.
(0,10), (1,13), (2,16), (3,19)
What would the graph of a relation look like.

3. Domain- set of all inputs or x – coordinates of the ordered pairs
Range- the set of all outputs, or y- coordinates of the ordered pairs
Find the domain and range of the relation
(2,4), (3,4.5), (4,7.5), (5,7), (6,5), (6, 7.5)

4. Mapping diagram- links elements of the domain with corresponding elements of the range.
(0,10), (1,13), (2,16), (3,19)
0 10
1 13
2 16
3 19

5. A function is a relation in which each element of the domain is paired with exactly one element in the range. 7

6. You can tell if a relation is a function by its graph.
Vertical line test- if a vertical line passes through at least two points on the graph, the relation is not a function.
Ex) 4 on pg 23

7. A functional rule expresses an output value in terms of an input value.
Examples of functional rules.
y = 2x f(x) = x + 5 C = ∏d
Output Input

8. Functional notation f(x) is read “f of x”
Note that f(x) does not mean f times x.
f(x) = 2x + 3
You can make ordered pairs using the rule.
Find f(2) and f(-½)

9. Assignment 2-44 even, 63 on pg 59-60