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Chapter 9 - XYZ Custom Plus

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The Distributive Property<br />

and Algebraic Expressions<br />

We recall that the distributive property from Section 1.5 can be used to find the<br />

area of a rectangle using two different methods.<br />

x 3<br />

4<br />

x 3<br />

Area 5 4(x ) 1 4(3) Area 5 4(x 1 3)<br />

5 4x 1 12 5 4x 1 12<br />

Since the areas are equal, the equation 4(x 1 3) 5 4(x ) 1 4(3) is a true statement.<br />

4<br />

9.1<br />

Objectives<br />

A Apply the distributive property to<br />

an expression.<br />

B Combine similar terms.<br />

C Find the value of an algebraic<br />

expression.<br />

D Solve applications involving<br />

complementary and supplementary<br />

angles.<br />

Examples now playing at<br />

MathTV.com/books<br />

A<br />

The Distributive Property<br />

Example 1<br />

Apply the distributive property to the expression:<br />

5(x 1 3)<br />

Practice Problems<br />

1. Apply the distributive property<br />

to the expression 6(x 1 4).<br />

Solution<br />

Distributing the 5 over x and 3, we have<br />

5(x 1 3) 5 5(x) 1 5(3) Distributive property<br />

5 5x 1 15 Multiplication<br />

Remember, 5x means “5 times x.”<br />

The distributive property can be applied to more complicated expressions involving<br />

negative numbers.<br />

Example 2<br />

Multiply: 24(3x 1 5)<br />

2. Multiply: 23(2x 1 4)<br />

Solution<br />

Multiplying both the 3x and the 5 by 24, we have<br />

24(3x 1 5) 5 24(3x) 1 (24)5 Distributive property<br />

5 212x 1 (220) Multiplication<br />

5 212x 2 20 Definition of subtraction<br />

Notice, first of all, that when we apply the distributive property here, we multiply<br />

through by 24. It is important to include the sign with the number when we use<br />

the distributive property. Second, when we multiply 24 and 3x, the result is 212x<br />

because<br />

24(3x) 5 (24 ? 3)x Associative property<br />

5 212x Multiplication<br />

Answers<br />

1. 6x 1 24 2. 26x 2 12<br />

9.1 The Distributive Property and Algebraic Expressions<br />

511

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