lesson 5 opposites and absolute value

8/13/2019 Lesson 5 Opposites and Absolute Value

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Mr. C Chapter 1: Lesson 5: Opposites and Absolute Value 1

Lesson 5: Opposites and Absolute Value

OppositesTwo numbers that are the same distance from zero on a number line, but on opposite sides of zero.

Find the Opposite of an IntegerSteps1. Graph the number on the number line2. Determine how far is the number from zero.

This is also called the magnitude of the number.

3. Find the opposite.The opposite of a number must be the same distance from zero as the original number, but in the oppositedirection.

Example 1

Find the opposite of 7.

Step 1: Graph the number on the number line.

Step 2: Determine how far the number is from zero.

Step 3: Find the opposite.

Solution

The opposite of 7 is -7.


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Practice 1Find the opposite of the following numbers.

-3

The opposite of anegative number isalsways positive.

Answer: 3

5

The opposite of apositive number isalsways negative.

Answer: -5

12 14

9 -10 23 -1

-13 72 -25 -51

36 15 17 -9

-87 -31 74 23

Answers

1) _____3____2) ____-5____3) __________4) __________5) __________6) __________7) __________8) __________9) __________10)__________11)__________12)__________13)__________14)__________15)__________16)__________17)__________18)__________19)__________20)__________


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Absolute ValueThe distance a number is from zero on a number line.

Important Facts1. The distance from zero is always positive.2. Show absolute value with vertical lines on each side of the number.3. | 2 | Means the absolute value of 2.

Reading Absolute Value

Example 2

5 The absolute value of 5.

51- The absolute value of negative 15.

- 8 The opposite of the absolute value of 8.

- 65- The opposite of the absolute value of negative 65.

Practice 2- Writing absolute value in words

1000

0

- 7

- 18

- 31

- 01-

- 78

- 25


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Solving Absolute Value ProblemsThe absolute value of a number is the distance a number is from zero on a number line.

Important FactsThe absolute value of a mumber is always positive because the distance from zero is alwas positive.

Steps1. Graph the number inside the absolute value bars.2. Determine the distance from the number to zero.3. Record the answerExample 3Find the absolute value of 3.

1. Graph the number inside the absolute value bars 3 .

2. Determine the distance from the number to zero.

3. Answer.The absolute value of 3 is 3. 33

Example 3Find the absolute value of - 3.

1. Graph the number inside the absolute value bars 3- .

2. Determine the distance from the number to zero.

3. Answer.The absolute value of -3 is 3. 33-


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Practice 3Simplify each expression.

8-

The absolute valueof -8 is 8 because -8is 8 units from zero.

88-

5

The absolute valueof 5 is 5 because 5 is5 units from zero.

55

12- 14

9 10- 18 - 1-

- 13- 72- 25 51

36 18- 100 91-

- 87- 69 75 23-

Answers

1) ___8______2) ____5_____3) __________4) __________5) __________6) __________7) __________8) __________9) __________10)__________11)__________12)__________13)__________14)__________15)__________16)__________17)__________18)__________19)__________20)__________


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Lesson 5: Test Your Knowledge

Write an integer to represent each quantity

1) A loss of $45. 2) 10 min before themovie.

3) 30 degrees below zero.

4) A withdraw of $300. 5) A deposit of $1000. 6) A debt of $500.

7) An elevation of 1300 ft. 8) 500 ft below sea level. 9) A decrease of 50 ft.

Write an integer to represent the opposite of each point

10)A B C 11)D E F 12)G H I

Simplify each expression

13) 22- 14)The absolute value of 73. 15) 0

16)The opposite of theabsolute value of 52.

17)- 365- 18) 8

19)What is the absolute valueof any number?

20)The absolute value ofnegative 19.

21)The opposite of theabsolute

Answers1) __________2) __________3) __________4) __________5) __________6) __________7) __________8) __________9) __________10)__________11)__________12)__________13)__________14)__________15)__________16)__________17)__________18)__________19)__________20)__________21)__________

lesson 5 opposites and absolute value

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