Course 2, Lesson 3-4

Lesson 4: Multiply Integers

Chapter 3

Course 2, Lesson 3-4

WHAT happens when you add,

subtract, multiply, and divide integers?

• To multiply integers with different signs
• To multiply integers with the same sign

Course 2, Lesson 3-4

Lesson 4: Multiply Integers

Course 2, Lesson 3-4

Multiply Integers with Different Signs

Words The product of two integers with different signs is negative.

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Examples 6(−4) = −24 −5(7) = −35

1

Step-by-Step Example

1.

Find 3(–5).

3(–5) = –15

The integers have different signs. The product is negative.

Answer

Need Another Example?

Find 5(–4).

–20

Step-by-Step Example

1

2.

Find –6(8).

–6(8) = –48

The integers have different signs. The product is negative.

Answer

Need Another Example?

Find –3(9).

–27

Course 2, Lesson 3-4

Multiply Integers with the Same Sign

Words The product of two integers with the same sign is positive.

​

Examples 2(6) = 12 −10(−6) = 60

​

Step-by-Step Example

1

3.

Find –11(–9).

–11(–9) = 99

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

Answer

Need Another Example?

Find –6(–8).

48

1

2

Step-by-Step Example

4.

Find (–4)².

(–4)² = (–4)(–4)

There are two factors of –4.

= 16

The product is positive.

Answer

Need Another Example?

Find (–8)²

64

1

2

3

Step-by-Step Example

5.

Find –3(–4)(–2).

–3(–4)(–2) = [–3(–4)](–2)

Associative Property

= 12(–2)

–3(–4) = 12

= –24

12(–2) = –24

Answer

Need Another Example?

Find (–2)(–5)(–6).

–60

Step-by-Step Example

1

6.

A submersible is diving from the surface of the water at a rate of 90 feet per minute. What is the depth of the submersible after 7 minutes?

The submersible descends 90 feet per minute. After 7 minutes, the vessel will be at 7(–90) or –630 feet. The submersible will descend to 630 feet below the surface.

Answer

Need Another Example?

A mine elevator descends at a rate of 200 feet per minute. Write a multiplication expression to represent the total distance descended after four minutes. Then find the product and explain its meaning.

4(–200); –800; In four minutes,

the elevator will descend 800 feet.

How did what you learned

today help you answer the

WHAT happens when you add,

subtract, multiply, and divide integers?

Course 2, Lesson 3-4

How did what you learned

today help you answer the

WHAT happens when you add,

subtract, multiply, and divide integers?

Course 2, Lesson 3-4

Sample answers:

• The product of integers with different signs is negative.
• The product of integers with the same sign is positive.

​

Evaluate:

​

(-2)(8) =

(-6)(-3) =

(-4)(-2)(-5) =

Course 2, Lesson 3-4

Ratios and Proportional Relationships