6th Grade Math Textbook, Fundamentals

 &KDSWHU

3-3

Model Properties of Inequality

Objective To use algebra tiles and number lines to model properties of inequality

Tamika is 5 years old and her brother
Rashid is 3 years old. The table at
the right shows inequalities that
compare their:

• present ages


• ages one year from now


• ages two years ago

All inequalities in the table show that Tamika’s age is
greater than her brother’s age. This example illustrates
the Addition and Subtraction Properties of Inequality.

You can use algebra tiles to model the Addition and

Subtraction Properties of Inequality.

Addition Property of Inequality

3  53  1  5  1 4  6

true statement true statement

Subtraction Property of Inequality

5  35  2  3  2 3  1

true statement true statement

You can use algebra tiles to model adding a negative

number to both sides of an inequality.

4  14 ( 2 ) 1 ( 2 ) 2  3

true statement true statement

You can also use algebra tiles and number lines to model multiplyingand

dividingboth sides of an inequality by a positive or a negative number.

Ages

Present One Year From Now Two Years Ago

5  35  1  3  1

6  4

5  2  3  2

3  1

3  53  1  5  1

4  6

3  2  5  2

1  3

Add 1 to

both sides

Subtract 2 from

both sides

Add 2 to

both sides

Key Concept

When you add the same number

to both sides of an inequality,

you get a true statement.

Addition Property of Inequality

Key Concept

When you subtract the same number

from both sides of an inequality,

you get a true statement.

Subtraction Property of Inequality

Remember:

zero pair

1 (1)  0