## Math 6 Chapter 2 Lesson 4: Add two integers with the same sign

## 1. Summary of theory Tóm

\(a,b \in \mathbb{Z},\,ab > 0\)

**a) Add two positive integers** (is the addition of two natural numbers)

|a| + |b| = a + b

**b) Add two negative integers:**

a + b = -(|a| + |b|)

⇒ To add two negative integers, add their absolute values and put a “-” sign in front of the result.

## 2. Illustrated exercise

**Question 1: **Calculate the value of the expression

a. x + (-10), know x = -28

b. (-267) + y, knowing y = -33.

__Solution guide__

a. (-28) + (-10) = – (28 + 10) = -38

b. (-267) + (-33) = – (267 + 33) = -300

**Verse 2: **Calculate

a. (-7) + (-328)

b. 12 + |-23|

c. |-46| + |+12|

__Solution guide__

a. (-7) + (-328) = -335

b. 12 + |-23| = 12 + 23 = 35

c. |-46| + |+12| = 46 + 12 = 58

## 3. Practice

### 3.1. Essay exercises

**Question 1: **Write the next two numbers of each of the following numbers:

a. 2, 4, 6, 8, ….

b. -3, -5, -7, -9,…

**Verse 2: **Give the meanings of the following sentences: Temperature increase t^{0}C, if t = 12, -3, 0

**Question 3: **Compare and withdraw comments

a. |3 + 17| with |3| + |17|

b. |-3 + (-17)| with |-3| + |-17|

### 3.2. Multiple choice exercises Bài

**Question 1: **State the rule for adding two negative integers?

**Verse 2: **Fill in the blanks with appropriate punctuation: (-4) + (-6) … (-6)

A. <

B. >

C. =

D. \( \ge \)

**Question 3: **The current temperature of the chill room is -4oC. What will be the room temperature when reduced by 9oC?

A. 5^{o}OLD

B. -13^{o}OLD

C. 9^{o}OLD

D. 13^{o}OLD

**Question 4: **The result of the calculation (-25) + |-12| – 4 is?

A. -41

B. -17

C. 9

D. 33

**Question 5: **Find an integer x knowing that x is seven units greater than 0 0

A. -6

B. -7

C. 7

D. -1

## 4. Conclusion

Through this lesson Add two integers with the same sign, you need to complete some of the objectives given by the lesson such as:

- Add two positive integers
- Add two negative integers
- Apply theory to do some exercises related to adding two integers with the same sign

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