Lesson 2.6 - Multiplying Integers

Five-Minute Check (over Lesson 2–5) Main Idea Key Concept: Multiply Integers with Different Signs Example 1: Multiple Integers with Different Signs Example 2: Multiple Integers with Different Signs Key Concept: Multiply Integers with Same Sign Example 3: Multiply Integers with the Same Sign Example 4: Multiply Integers with the Same Sign Example 5: Multiply Integers with the Same Sign Example 6: Use Integers to Solve a Problem Example 7: Evaluate Expressions

• Multiply integers.

Multiply Integers with Different Signs Find 5(–4). 5(–4) = –20

Answer: –20

The integers have different signs. The product is negative.

Find 3(–5). A. –15 B. –2

A B C 0% D

0% D

A

D. 15

0% B

0%

1. 2. 3. 4.

C

C. 2

Multiply Integers with Different Signs Find –3(9). –3(9) = –27

Answer: –27

The integers have different signs. The product is negative.

Find –5(7). A. –35 B. 2

A B C 0% D

0% D

A

D. 35

0% B

0%

1. 2. 3. 4.

C

C. 12

Multiply Integers with the Same Sign Find –6(–8). –6(–8) = 48

Answer: 48

The integers have the same sign. The product is positive.

Find –4(–7). A. –28 B. –11

A B C 0% D

0% D

A

D. 28

0% B

0%

1. 2. 3. 4.

C

C. 11

Multiply Integers with the Same Sign Find (–8)2.

(–8)2 = (–8)(–8) = 64

Answer: 64

There are two factors of –8. The product is positive.

Find (–5)2. A. –25 B. –10

A B C 0% D

0% D

A

D. 25

0% B

0%

1. 2. 3. 4.

C

C. 10

Multiply Integers with the Same Sign Find –2(–5)(–6).

–2(–5)(–6) = [–2(–5)](–6) Associative Property = 10(–6) –2(–5) = 10 Answer: –60

= –60 The product is negative.

Find –7(–3)(–4). A. 84 B. –14

A B C 0% D

0% D

A

D. –84

0% B

0%

1. 2. 3. 4.

C

C. 14

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.

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? A. –$468 B. $468

1. 2. 3. 4.

C. –$84 0% D

0% C

0% B

D. $84

A

0%

A B C D

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

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.

Answer: 120

ALGEBRA Evaluate xyz if x = –6, y = –2, and z = 4. A. –48 B. –4

A B C 0% D

0% D

A

D. 48

0% B

0%

1. 2. 3. 4.

C

C. 0

End of the Lesson

Pg. 110-111, # 14-36 even, 38-44, 46-48

Five-Minute Check (over Lesson 2–5) Image Bank Math Tools

Adding Integers Comparing and Ordering Integers Subtracting Positive and Negative Integers

(over Lesson 2-5)

Find 4 – 5. A. –9 B. –1 C. 1 D. 9

1. 2. 3. 4.

A B C D

(over Lesson 2-5)

Find –14 – 34. A. –48 B. –20

A B C 0% D

0% D

A

D. 48

0% B

0%

1. 2. 3. 4.

C

C. 20

(over Lesson 2-5)

Find –45 – (–8). A. –53 B. –37

A B C 0% D

0% D

A

D. 53

0% B

0%

1. 2. 3. 4.

C

C. 37

(over Lesson 2-5)

Evaluate c – b for b = 3 and c = –1. A. 4 B. 2

A B C 0% D

0% D

0% B

D. –4

A

0%

1. 2. 3. 4.

C

C. –2

(over Lesson 2-5)

Evaluate 9 – a for a = –2. A. 11 B. 7

A B C 0% D

0% D

A

D. –11

0% B

0%

1. 2. 3. 4.

C

C. –7

(over Lesson 2-5)

What is –4 subtracted from –3? A. –7 B. –1 A B C 0% D

0% D

0% B

D. 7

A

0%

1. 2. 3. 4.

C

C. 1