 # Warm Up Simplify each expression. Factor the expression.

## Presentation on theme: "Warm Up Simplify each expression. Factor the expression."— Presentation transcript:

Warm Up Simplify each expression. Factor the expression. 3. x2 + 5x + 6

Simplifying Rational Expressions
12-3 Simplifying Rational Expressions Holt Algebra 1

Objectives Simplify rational expressions.
Identify excluded values of rational expressions.

A rational expression is an algebraic expression whose numerator and denominator are polynomials. The value of the polynomial expression in the denominator cannot be zero since division by zero is undefined. This means that rational expressions may have excluded values.

A rational expression is undefined when the denominator is equal to 0
A rational expression is undefined when the denominator is equal to 0. A number that makes a rational expression undefined is called an excluded value.

Example 1A: Identifying Excluded Values
Find any excluded values of each rational expression. g + 4 = 0 Set the denominator equal to 0. g = –4 Solve for g by subtracting 4 from each side. The excluded value is –4.

Example 1C: Identifying Excluded Values
Find any excluded values of each rational expression. y2 + 5y + 4 = 0 Set the denominator equal to 0. (y + 4)(y + 1) = 0 Factor y + 4 = 0 or y + 1 = 0 Use the Zero Product Property. y = –4 or y = –1 Solve each equation for y. The excluded values are –4 and –1.

A rational expression is in its simplest form when the numerator and denominator have no common factors except 1. Remember that to simplify fractions you can divide out common factors that appear in both the numerator and the denominator. You can do the same to simplify rational expressions.

Example 2A: Simplifying Rational Expressions
Simplify each rational expression, if possible. Identify any excluded values. 4 Factor 14. Divide out common factors. Note that if r = 0, the expression is undefined. Simplify. The excluded value is 0.

Example 2B: Simplifying Rational Expressions
Simplify each rational expression, if possible. Identify any excluded values. Factor 6n² + 3n. Divide out common factors. Note that if n = , the expression is undefined. 3n; n ≠ Simplify. The excluded value is

Be sure to use the original denominator when finding excluded values
Be sure to use the original denominator when finding excluded values. The excluded values may not be “seen” in the simplified denominator. Caution

Divide out common factors.
Check It Out! Example 3 Simplify each rational expression, if possible. a. b. Factor the numerator and the denominator when possible. Divide out common factors. Simplify.