Rational Equations Section 8-6
Objectives Solve rational equations with one variable by CROSS MULTIPLYING Check answers for Extraneous Solutions
Extraneous Solutions Any solution that makes a denominator ZERO does not check. (Extraneous)
Solving Rational Equations Two basic methods 1. Cross Multiply two rational expressions to solve them 2. Set equation equal to ZERO and then get Common Denominator
Today Cross Multiplying Method
Cross Multiplication Method
Example 2
Example 3
Solve a rational equation by cross multiplying EXAMPLE 1 Solve a rational equation by cross multiplying Solve: 3 x + 1 = 9 4x + 1 3 x + 1 = 9 4x + 1 Write original equation. 3(4x + 5) = 9(x + 1) Cross multiply. 12x + 15 = 9x + 9 Distributive property 3x + 15 = 9 Subtract 9x from each side. 3x = – 6 Subtract 15 from each side. x = – 2 Divide each side by 3. The solution is –2. Check this in the original equation. ANSWER
Homework WS 12-5