Chapter 1: Variables, Function Patterns, and Graphs

1.4Patterns and Functions

Vocabulary

• Function– A relationship that assigns exactly one output value for

each input value– For each input, there is only ONE corresponding output

• Function Rule– An equation that describes a functional relationship

“Function Machine”

Example 1• Suppose you are washing and drying clothes at a

self-service laundry. The relationship between the number of loads (input) and the cost (output) is a function. Use the table to write a function rule.Number of Loads 1 2 3 4

Cost $2.75 $5.50 $8.25 $11.00

Example 1a• Write a function rule for the relationship between

the number of hours (input) and the number of miles (output).

Hours Total Miles

1 60

2 120

3 180

4 240

Example 2• The relationship between the number of houses

and the number of toothpicks is a function. Use the table to write a function rule.

Number of Houses

Total Number of Toothpicks

1 6

2 11

3 16

4 23

Vocabulary

• Dependent variable– Depends on the value of the independent variable

• Independent variable– Will occur regardless of what’s going on around it

Example 3• The table and graph model a function relating the

storage capacity of a memory stick and its cost. Identify the independent and dependent quantities.

Memory (MB)

Cost ($)

32 19

64 29

128 39

256 49

Example 3a

• The cooking time for an unstuffed turkey is about 20 minutes per pound. What are the independent quantity and the dependent quantity for this situation?

Example 4

• Maria earns $7 per hour for baby-sitting after school and on Saturday. She works no more than 16 hours per week.

• Identify the independent and dependent quantities for this situation.

Example 4

• Maria earns $7 per hour for baby-sitting after school and on Saturday. She works no more than 16 hours per week.

• Find reasonable domain and range values for this situation.

Example 4a• Charlie downloads songs for $.75 each. He has

between $3.00 and $6.00 to spend on songs. Identify the independent and dependent quantities for this situation and find reasonable domain and range values.

Homework

• P. 29

• 2-16 even