• linear function

• Represent linear functions using function tables and graphs.

MUSIC During a clearance sale, a music store is selling CDs for $3 and tapes for $1. Graph the function 3x + y = 6 to find how many CDs and tapes Bill can buy with $6.

Graph a Function

First, rewrite the equation by solving for y.

3x + y = 6 Write the equation.

3x – 3x + y = 6 – 3xSubtract 3x from each side.

y = 6 – 3xSimplify.

Choose values for x and substitute them to find y. Then graph the ordered pairs.

Answer: The solutions are 0 CDs and 6 tapes, 1 CD and 3 tapes, or 2 CDs and 0 tapes.

Graph a Function

1. A

2. B

3. C

4. D0% 0%0%0%

BAKE SALE During a bake sale, a plate of brownies is sold for $2 and a plate of cookies is sold for $1. Graph the function 2x + y = 4. Which is not a combination of plates of brownies and cookies Craig can buy with $4?A. 2 plates of brownies,

0 plates of cookies

B. 1 plate of brownies, 2 plates of cookies

C. 1 plate of brownies, 3 plates of cookies

D. 0 plate of brownies, 4 plates of cookies

Graph a Function

Graph y = x – 3.

Step 1 Choose some values for x. Make a function table. Include a column of ordered pairs of the form (x, y).

Graph a Function

Step 2 Graph each ordered pair.

Draw a line that passes through each point.

Answer:

Note that the ordered pair for any point on this line is a solution of y = x – 3. The line is the complete graph of the function.

Graph a Function

Check It appears from the graph that (–1, –4) is also a solution. Check this by substitution.

y = x – 3 Write the function.

?–4 = –1 – 3 Replace x with –1 and y with –4.

–4 = –4 Simplify.

1. A

2. B

3. C

4. D

A B C D

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Graph y = x –2.

A. B.

C. D.

Which line graphed below best represents the table of values for the ordered pairs (x, y)?

A. B.

C. D.

Solve the Item

The values in the table represent the ordered pairs (0, 1), (1, 3), (2, 5), and (3, 7).

Answer: D

Read the Item

You need to decide which of the four graphs represents the data in the table.

Test the ordered pairs with each graph. Graph D is the only graph which contains all these ordered pairs. The answer is D.

1. A

2. B

3. C

4. D0% 0%0%0%

Which line graphed below best represents the table of values for the ordered pairs (x, y)?

A. B.

C. D.

1. A

2. B

3. C

4. D

A B C D

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(over Lesson 9-2)

A. 4

B. 9

C. 15

D. 36

Find f(3) if f(x) = x + 12.

1. A

2. B

3. C

4. D

A B C D

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(over Lesson 9-2)

Find f(5) if f(x) = 4x.

A. AnsA

B. AnsB

C. AnsC

D. AnsD

1. A

2. B

3. C

4. D

A B C D

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(over Lesson 9-2)

A. 2

B. 11

C. 12

D. 13

Find f(6) if f(x) = 2x – 1.

1. A

2. B

3. C

4. D

A B C D

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(over Lesson 9-2)

A. –23

B. –21

C. 21

D. 23

Find f(–7) if f(x) = –3x + 2.

1. A

2. B

3. C

4. D0% 0%0%0%

Elizabeth is buying candles. They are $5.43 each. She is not sure how many she wants to buy. Write a function to calculate the total cost for any given number of candles.

(over Lesson 9-2)

A. f(x) = 5.43x

B.

C. f(x) = 5.43 + x

D. f(x) = 5.43 – x

1. A

2. B

3. C

4. D

A B C D

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(over Lesson 9-2)

A. y = x + 45

B. y = 3x

C. y = 3x + 4

D. y = 2x + 3

Which function matches the function table?