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Section 6.4 Rational Equations. Solving Rational Equations Clearing Fractions in an Equation Restricted Domains (and Solutions) The Principle of Zero Products The Necessity of Checking Rational Equations and Graphs. A Rational Equation in One Variable May Have Solution(s).
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Section 6.4 Rational Equations • Solving Rational Equations • Clearing Fractions in an Equation • Restricted Domains (and Solutions) • The Principle of Zero Products • The Necessity of Checking • Rational Equations and Graphs 6.4
A Rational Equation in One VariableMay Have Solution(s) • A Rational Equation contains at least one Rational Expression. Examples: • All Solution(s) must be tested in the Original Equation 6.4
False Solutions • Warning: Clearing an equation may add a False Solution • A False Solution is one that causes an untrue equation, or a divide by zero situation in the original equation • Before even starting to solve a rational equation, we need to identify values to be excluded • What values need to be excluded for these? • t ≠ 0 a ≠±5 x ≠ 0 6.4
Clearing Factions from Equations • Review: Simplify- Clear a Complex Fraction by • Multiplying top and bottom by the LCD • Solve - Clear a Rational Equation by • Multiplying both sides by the LCD • Then solve the new polynomial equation using the principle of zero products 6.4
The Principle of Zero Products • Covered in more detail in Section 5.8 • When a polynomial equation is in formpolynomial = 0you can set each factor to zero to find solution(s) • Example – What are the solutions to: • x2 – x – 6 = 0 • (x – 3)(x + 2) = 0 • x – 3 = 0 x = 3 and x + 2 = 0 x = -2 6.4
Clearing & Solving a Rational Equation What gets excluded? x ≠ 0 What’s the LCD? 15x What’s the solution? 6.4
A Binomial Denominator What gets excluded? x ≠ 5 What’s the LCD? x – 5 What’s the solution? 6.4
Another Binomial Denominator What gets excluded? x ≠ 3 What’s the LCD? x – 3 What’s the solution? x = -3 (x = 3 excluded) 6.4
Different Binomial Denominators What gets excluded? x ≠ 5,-5 What’s the LCD? (x – 5)(x + 5) What’s the solution? x = 7 6.4
Functions as Rational Equations What gets excluded? x ≠ 0 What’s the LCD? x What’s the solution? x = 2 and x = 3 6.4
What Next? • 6.5Solving Applications of Rational Equations 6.4