Fundamentals of Math

Fundamentals of Mathematics

4.5 Multiplying Binomials Let's learn a new technique for simplifying functions (or expressions) - multiplying a binomial by another binomial. First, we will begin by defining what a binomial is - a binomial is an algebraic expression of the sum or difference of the two terms. When multiplying binomials, use the distributive property. A common acronym for remembering this is known as FOIL .

( + 1)( + 2)

F:

First Term × First Term

O: Outer Term × Outer Term

I: Inner Term × Inner Term

L:

Last Term × Last Term

After you multiply everything together, combine like terms to simplify.

Example 4.5

Simplify ( − 2)( + 5)

Step 1: Multiply all the terms together using the distributive property (or FOIL).

F

O

I

L

×

× 5

−2 ×

−2 × 5

2

5

−2

−10

Step 2: Add or subtract all the terms together and combine like terms.

2 + 5 − 2 − 10 = 2 + 3 − 10

Practice 4.5

Directions: Find the product of each expression.

1. (2 + 3)(2 − 1)

2. (4 + 1)(5 + 8)

3. ( − 7)( − 3)

4. ( − 1)(2 + 5)

Answer Key on Page 122

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