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2.12: Absolute Value

Difficulty Level: Advanced / Basic / At Grade Created by: CK-12
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What is the absolute value represented by the number line below?

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Khan Academy Absolute Value Equations

Guidance

Absolute value in the real number system is the distance from zero on the number line. It is always a positive number.

Absolute value is always written as |x| . Using this notation can be translated as “the positive value of x ”.

Example A

|-7|=?

Solution:

|-7|=7

Example B

|7-15|=?

Solution:

|7-15|&=?\\|-8|&=?

|-8|=8

Example C

|-9|-|-2| = ?

Solution:

|-9|-|-2| &= ?\\|-9|-|-2| &= 9-2\\|-9|-|-2| &= 7

Concept Problem Revisited

What is the absolute value represented by the number line below?

Remember the definition of absolute value in the real number system is the distance from zero on the number line. Let’s look at the distance from the -6 to zero.

Therefore |-6|=6 .

Vocabulary

Absolute Value
Absolute value in the real number system is the distance from zero on the number line. It is always a positive number and is represented using the symbol |x| .

Guided Practice

1. |-50|=?

2. \big |- \frac{4}{5} \big |=?

3. |-3|-|-4|=?

Answers:

1. |-50|=?

|-50|=50

2. \big | -\frac{4}{5} \big |=?

\big | - \frac{4}{5}\big |=\frac{4}{5}

3.

|-3|-|-4| &=?\\|-3|-|-4| &=3-4\\|-3|-|-4| &= -1

Practice

Evaluate each of the following using a number line:

  1. |-4.5|=?
  2. |-1|=?
  3. \big | -\frac{1}{3} \big |=?
  4. |4|=?
  5. |-2|=?

Evaluate each of the following:

  1. |-1|+|3|=?
  2. |5|-|-2|=?
  3. \big | -\frac{1}{2}\big |+ \big | - \frac{2}{3} \big |=?
  4. |-2.4|-|-1.6|=?
  5. |-3|-|-2.4|=?

Evaluate each of the following:

  1. |2-4|=?
  2. |5-6|=?
  3. \big | -\frac{1}{2} - \frac{5}{6}\big |=?
  4. |2.3-3.7|=?
  5. |7.8 - 9.4|=?

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Difficulty Level:

Advanced

Grades:

Date Created:

Jan 16, 2013

Last Modified:

Mar 10, 2014
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MAT.ALG.156.2.L.3

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