7th Grade Math

Get ConnectED

Rates and Functions

PART A BCD E

Multi-Part

Lesson 1

GLE 0706.3.2

Understand and compare

various representations of

relations and functions.

GLE 0706.3.3 Understand

the concept of function as a

rule that assigns to a given

input one and only one

number (the output). Also

addresses SPI 0706.3.2.

Relations and Functions

A relation expresses how objects in one group, inputs, are assigned or

related to objects in another group, outputs.

The mapping diagram below shows three possible relations. If each

item, or input, has only one price, or output, then the relation is also a

function.

Function Function Not a Function

Input Output

Binder

Gel Pens

Notebook

$3.00

$1.50

$0.75

Input Output

Binder

Gel Pens

Notebook

$3.00

$0.75

Input Output

Binder

Gel Pens

Notebook

$3.00

$1.50

$0.75

The first two relations are functions because each item has only one

price. The third relation is not a function because the binder has two

prices, $3 and $1.50.

Copy the relation diagram. Input Output

1

3

6

8

2

5

7

10

Draw lines from the input values

to the output values so that the

relation is a function.

Copy the relation diagram from

Step 1. Draw lines from the

input values to the output values

so that the relation is not a function.

the Results

1. A relation can be written as a set of ordered pairs, with the input
   as the x-coordinate and the output as the y-coordinate. For each
   relation diagram you drew in the Activity above, write the relation
   as a set of ordered pairs.


2. Describe why each relation is or is not a function. Explain your
   reasoning in terms of the ordered pairs.

Lesson 1A Rates and Functions 377

Main Idea

Determine whether a

relation is a function.

377_384_C07_L1_895130.indd 377 12/31/09 4:23 PM