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Intermediate Algebra 098A. Chapter 7 Rational Expressions. Intermediate Algebra 098A 7.1. Introduction to Rational Expressions. Definition: Rational Expression. Can be written as Where P and Q are polynomials and Q(x) is not 0. Determine Domain of rational function.
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Intermediate Algebra 098A Chapter 7 Rational Expressions
Intermediate Algebra 098A 7.1 • Introduction • to • Rational Expressions
Definition: Rational Expression • Can be written as • Where P and Q are polynomials and Q(x) is not 0.
Determine Domain of rational function. • 1. Solve the equation Q(x) = 0 • 2. Any solution of that equation is a restricted value and must be excluded from the domain of the function.
Graph • Determine domain, range, intercepts • Asymptotes
Graph • Determine domain, range, intercepts • Asymptotes
Calculator Notes: • [MODE][dot] useful • Friendly window useful • Asymptotes sometimes occur that are not part of the graph. • Be sure numerator and denominator are enclosed in parentheses.
Simplifying Rational Expressions to Lowest Terms • 1. Write the numerator and denominator in factored form. • 2. Divide out all common factors in the numerator and denominator.
Objective: • Simplify a Rational Expression.
Denise Levertov – U. S. poet • “Nothing is ever enough. Images split the truth in fractions.”
Robert H. Schuller • “It takes but one positive thought when given a chance to survive and thrive to overpower an entire army of negative thoughts.”
Intermediate Algebra 098A 7.2 • Multiplication • and • Division
Multiplication of Rational Expressions • If a,b,c, and d represent algebraic expressions, where b and d are not 0.
Procedure • 1. Factor each numerator and each denominator completely. • 2. Divide out common factors.
Procedure • 1. Factor each numerator and each denominator completely. • 2. Divide out common factors.
Procedure for Division • Write down problem • Invert and multiply • Reduce
Objective: • Multiply and divide rational expressions.
John F. Kennedy – American President • “Don’t ask ‘why’, ask instead, why not.”
Intermediate Algebra 098A 7.3 • Addition • and • Subtraction
Objective • Add and Subtract • rational expressions with the same denominator.
Procedure adding rational expressions with same denominator • 1. Add or subtract the numerators • 2. Keep the same denominator. • 3. Simplify to lowest terms.
Intermediate Algebra 098A 7.4 • Adding and Subtracting Rational Expressions with unlike Denominators
LCMLCD • The LCM – least common multiple of denominators is called LCD – least common denominator.
Objective • Find the lest common denominator (LCD)
Determine LCM of polynomials • 1.Factor each polynomial completely – write the result in exponential form. • 2. Include in the LCM each factor that appears in at least one polynomial. • 3. For each factor, use the largest exponent that appears on that factor in any polynomial.
Procedure: Add or subtract rational expressions with different denominators. • 1. Find the LCD and write down • 2. “Build” each rational expression so the LCD is the denominator. • 3. Add or subtract the numerators and keep the LCD as the denominator. • 4. Simplify
Elementary Example • LCD = 2 x 3
Objective • Add and Subtract • rational expressions with unlike denominator.
Martin Luther • “Even if I knew that tomorrow the world would go to pieces, I would still plant my apple tree.”
Maya Angelou - poet • “Since time is the one immaterial object which we cannot influence – neither speed up nor slow down, add to nor diminish – it is an imponderably valuable gift.”
Intermediate Algebra 098A 7.5 • Equations • with • Rational Expressions
Extraneous Solution • An apparent solution that is a restricted value.
Procedure to solve equations containing rational expressions • 1. Determine and write LCD • 2. Eliminate the denominators of the rational expressions by multiplying both sides of the equation by the LCD. • 3. Solve the resulting equation • 4. Check all solutions in original equation being careful of extraneous solutions.
Graphical solution • 1. Set = 0 , graph and look for x intercepts. • Or • 2. Graph left and right sides and look for intersection of both graphs. • Useful to check for extraneous solutions and decimal approximations.
Thomas Carlyle • “Ever noble work is at first impossible.”
Intermediate Algebra 098A 7.6 • Applications • Proportions and Problem Solving • With • Rational Equations
Objective • Use Problem Solving methods including charts, and table to solve problems with two unknowns involving rational expressions.
Problems involving work • (person’s rate of work) x (person's time at work) = amount of the task completed by that person.
Work problems continued • (amount completed by one person) + (amount completed by the other person) = whole task
Intermediate Algebra 098A 7.7 • Simplifying Complex Fractions
Definition: Complex rational expression • Is a rational expression that contains rational expressions in the numerator and denominator.
Objective • Simplify a complex rational expression.
Procedure 1 • 1. Simplify the numerator and denominator if needed. • 2. Rewrite as a horizontal division problem. • 3. Invert and multiply • Note – works best when fraction over fraction.
Procedure 2 • 1. Multiply the numerator and denominator of the complex rational expression by the LCD of the secondary denominators. • 2. Simplify • Note: Best with more complicated expressions. • Be careful using parentheses where needed.
Paul J. Meyer • “Enter every activity without giving mental recognition to the possibility of defeat. Concentrate on your strengths, instead of your weaknesses…on your powers, instead of your problems.”