1. A

2. B

3. C

4. D

(over Lesson 2-5)

A. 4 B. 2 C. –2 D. –4

Evaluate c – b for b = 3 and c = –1.

Evaluate 9 – a for a = –2.

A. 11 B. 7 C. –7 D. –11

What is –4 subtracted from –3?

A. –7 B. –1 C. 1 D. 7

Main Idea

Key Concept: Multiply Integers with Different Signs

Key Concept: Multiply Integers with Same Sign

Example 6: Use Integers to Solve a Problem

Example 7: Evaluate Expressions

• Multiply integers (2.2.8B) (M8.A.3.3.1).

1. D

Use Integers to Solve a Problem

MINES A mine elevator descends at a rate of 300 feet per minute. How far below the earth’s surface will the elevator be after 5 minutes?

If the elevator descends 300 feet per minute, then after 5 minutes, the elevator will be at –300(5) or –1,500 feet. Thus, the elevator will descend to –1,500 feet.

Answer: After five minutes, the elevator will be 1,500 feet below the earth’s surface.

1. A

2. B

3. C

4. D

A. –$468

B. $468

C. –$84

D. $84

RETIREMENT Mr. Rodriguez has $78 deducted from his pay every month and placed in a savings account for his retirement. What integer represents a change in his savings account for these deductions after six months?

ALGEBRA Evaluate abc if a = –3, b = 5, and c = –8.

Answer: 120

Evaluate Expressions

abc = (–3)(5)(–8) Replace a with –3, b with 5, and c with –8.

= (–15)(–8) Multiply –3 and 5.

= 120 Multiply –15 and –8.

1. A

2. B

3. C

4. D

A. –48

B. –4

C. 0

D. 48

ALGEBRA Evaluate xyz if x = –6, y = –2, and z = 4.

REVIEW

1. Tamera owns 100 shares of a certain stock. Suppose the price of the stock drops by $3 per share. Write a multiplication expression to find the change in Tamera’s investment. Explain.

Evaluate each expression if f = -1, g = 7, and h = -10.

2. 5f

3. fgh

100(-3) = -300; Tamera’s investment if now worth $300 less than it was before the stock dropped.

5(-1)=-5

-1(7)(-10)=70

End of the Lesson

Five-Minute Check (over Lesson 2–5)

Image Bank

Math Tools

Adding Integers

Comparing and Ordering Integers

Subtracting Positive and Negative Integers