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# 8.5 Rational Expressions with Like Denominators PowerPoint PPT Presentation

8.5 Rational Expressions with Like Denominators. CORD Math Mrs. Spitz Fall 2006. Objective. Add and subtract rational expressions with like denominators. Upcoming. 8.5 Tuesday/Wednesday – Skip 8.6 8.7 Thursday 10/26 8.8 Friday 10/27 8.9 Monday 10/30 8.10 Tuesday/Wed

8.5 Rational Expressions with Like Denominators

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## 8.5 Rational Expressions with Like Denominators

CORD Math

Mrs. Spitz

Fall 2006

### Objective

• Add and subtract rational expressions with like denominators.

### Upcoming

• 8.5 Tuesday/Wednesday – Skip 8.6

• 8.7 Thursday 10/26

• 8.8 Friday 10/27

• 8.9 Monday 10/30

• 8.10 Tuesday/Wed

• Chapter 8 Review Wed/Thur

• Chapter 8 Test Friday

### Assignment

• Pg. 324 #4-41 all

• Midchapter Review pg. 325 #1-11

### Introduction

• To add or subtract fractions with like denominators, you add or subtract the numerators. Then you write the sum or difference over the common denominator.

You can use these same methods to add or subtract rational expressions.

### Ex. 1: Find

Since x + 2 is the common denominator, add the numerators.

### Ex. 2: Find

Add the additive inverse of a - 3.

Distributive Property

Remember when subtracting rational expressions to add the additive inverse of the second expression.

### Express in simplest form.

• When adding or subtracting fraction, sometimes the result can be expressed in simplest form.

The GCF of 4 and 8 is 4.

The GCF of 6 and 16 is 2.

### Ex. 3: Find

Since 3n+4 is the common denominator, subtract the numerators.

Combine like terms.

Factor out a 2 out of the numerator and cancel 3n+4 from both numerator and denominator.

### Ex. 4: Find

Rewrite 2 – x as x – 2 by multiplying by -1.

Remember

Simplify and combine like terms.

### Example 5: Application

• Find the measure of the perimeter of the rectangle.

### Ex. 5: Find the measure of the perimeter of the rectangle.

← Perimeter formula for rectangle.

← Substitute values.

← Distributive Property

← Combine like terms

← Factor out 2 as common factor and cancel terms that are same in numerator and denominator.

The measure of the perimeter is:

### Upcoming

• Midchapter Quiz – 20 points apiece so I can see how you are doing.

• Skipping 8.6

• 8.7 Rational expression with Unlike Denominators.

• 8.8 Mixed expressions and complex fractions.

• 8.9 Solving Rational Equations

• 8.10 Application: Formulas.

• Chapter 8 Review

• Chapter 8 Exam

• Binder Check. Make sure you have all notes from each section, or download off the web. You must recopy to get full credit.