Unit 4 Section 6 Writing a Function Rule.notebook
February 17, 2014
Bellringer
Complete the table below.
Function Linear Function
a.) f(x) = ­5x
b.) y = 4x ­ 3
c.) y = x2 + 6
d.) x = ­5
e.) y = 3
Constant Function Direct Variation
Unit 4 Section 6 Writing a Function Rule.notebook
Writing a Function Rule
Unit 4
February 17, 2014
Unit 4 Section 6 Writing a Function Rule.notebook
February 17, 2014
Reminder: Function notation:
Use the symbol f(x) in place of y.
You read f(x) as "f of x"
f(x) = 2x - 5
Output Values
(dependent variable)
Input Values
(independent variable)
You can write a function rule from charts by perceiving patterns
Unit 4 Section 6 Writing a Function Rule.notebook
February 17, 2014
Example 1: Write a function Rule for each table
x
y
x
y
2
3
­4
­6
­8
­10
­1
­3
4
­8
­12
­5
5
­10
­14
­7
6
­12
­16
­9
Unit 4 Section 6 Writing a Function Rule.notebook
February 17, 2014
Example 2: Write a function Rule for each table
x
y
x
y
1
6
1
2
2
8
2
5
3
10
3
8
4
12
4
11
5
14
5
14
Unit 4 Section 6 Writing a Function Rule.notebook
February 17, 2014
Example 3: Write a function Rule for each table
x
x
14
3
­8
­12
­2
­3
18
4
­16
­4
22
5
­20
­5
26
6
­24
­6
30
2
Unit 4 Section 6 Writing a Function Rule.notebook
February 17, 2014
Example 4: A car is 30 times longer than its scale model.
Write a function rule to describe the relationship.
a.)
b.)
If the model is 6 in long, how long is the car?
c.)
If the car is 60 in wide, how wide is the model?
Unit 4 Section 6 Writing a Function Rule.notebook
February 17, 2014
Example 5: You invest $209 to buy shirts and then sell them for $9.50
each.
a.) Write a function rule to determine your profit.
b.)
Use your rule to find profit after selling 24 shirts.
c.)
How many shirts do you need to sell to get back your investment?
Unit 4 Section 6 Writing a Function Rule.notebook
February 17, 2014
Example 6: Write a function rule to represent each situation.
A)
the total cost C for pounds of copper if each pound costs $3.57
B) the amount of your friend's allowance if the amount she recieves is
$2 more than three times the amount you recieve
C) the price p of a pizza is $6.95 plus $.95 for each topping t on the
pizza
D) A new book is being planned. It will have 24 pages of introduction.
Then it will have c 12-page chapters and 48 more pages at the end. Write
a rule that represents the total number of pages p in the book as a
function of the number of chapters. Suppost the book has 25 chapters.
How many pages will it have?
Unit 4 Section 6 Writing a Function Rule.notebook
Keystone Ready
The table below shows values of y as a
function of x.
x
y
2
10
6
25
14
55
26
100
34
130
Which linear equation best describes the
relationship between x and y?
A. y = 2.5x + 5
B. y = 3.75x + 2.5
C. y = 4x + 1
D. y = 5x
February 17, 2014