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Adding and Subtracting Rational Expressions. Essential Questions. How do we add and subtract rational expressions? How do we simplify complex fractions?. Holt McDougal Algebra 2. Holt Algebra 2.
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Adding and Subtracting Rational Expressions Essential Questions • How do we add and subtract rational expressions? • How do we simplify complex fractions? Holt McDougal Algebra 2 Holt Algebra 2
To add rational expressions with unlike denominators, rewrite both expressions with the LCD. This process is similar to adding fractions.
+ x – 3 2x x2 + 3x – 4 x + 4 Example 1: Adding Rational Expressions Add. Identify any x-values for which the expression is undefined. Factor the denominators. The LCD is (x + 4)(x – 1). Rewrite as one fraction. Simplify the numerator. Undefined at x = –4 and x = 1
+ 3x – 2 3x 3x – 3 2x –2 Example 2: Adding Rational Expressions Add. Identify any x-values for which the expression is undefined. Factor the denominators. The LCD is 6(x – 1). Rewrite as one fraction. Simplify the numerator. Undefined at x = 1
+ 2x + 6 x x2 + 6x + 9 x + 3 Example 3: Adding Rational Expressions Add. Identify any x-values for which the expression is undefined. Factor the denominators. The LCD is (x +3)(x + 3). Rewrite as one fraction. Simplify the numerator. Factor the numerator. Undefined at x = –3
Example 4: Subtracting Rational Expressions Subtract. Identify any x-values for which the expression is undefined. - - + Change the signs for subtraction. Factor the denominators. The LCD is (x +3)(x - 3). Rewrite as one fraction. Simplify the numerator. Factor the numerator. Undefined at x = –3 and x = 3
Example 5: Subtracting Rational Expressions Subtract. Identify any x-values for which the expression is undefined. - + Change the signs for subtraction. Factor the denominators. The LCD is (2x +5)(5x - 2). Rewrite as one fraction. Simplify the numerator. Undefined at x = 2/5 and x = –5/2
Example 6: Subtracting Rational Expressions Subtract. Identify any x-values for which the expression is undefined. - + + Change the signs for subtraction. Factor the denominators. The LCD is (x +8)(x - 8). Rewrite as one fraction. Simplify the numerator. Factor the numerator. Undefined at x = –8 and x = 8