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Quiz 8-5

Quiz 8-5. Simplify. 1. 2. 8-6 Solve Rational Equations. Vocabulary:. What does solve a single variable equation mean?. 3x + 2 = 11. What is a factor?. What is a least common multiple ?. Solving Rational Equations. Method #1: eliminate the denominators one at a time.

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Quiz 8-5

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  1. Quiz 8-5 Simplify 1. 2.

  2. 8-6 Solve Rational Equations

  3. Vocabulary: What does solve a single variable equation mean? 3x + 2 = 11 What is a factor? What is a least common multiple?

  4. Solving Rational Equations Method #1: eliminate the denominators one at a time. Method #2: Obtain common denominators for each term. Method #3: Find the least common multiple of all the denominators then multiply (left/right) by the LCM.

  5. Rational Equations How do you get the ‘5’ out of the denominator? x = 20 Multiply both sides by ‘5’ How do you get the ‘x’ out of the denominator? 2x = 10 Multiply both sides by ‘x’ x = ?

  6. Your turn: 1. Solve 2. Solve 3. Solve 4. Solve

  7. Variable on both sides of the equation How do you get the ‘x’ out of the left-side denominator? Multiply both sides by ‘x’ How do you get the (x+1) out of the right-side denominator? Multiply both sides by (x+1) Your turn: 5. solve

  8. Another example: The book teaches you to “cross-multiply” (yuck!) There is no property called “cross multiply”. There are the properties of equality. Cross multiplication is the result of multiplying both sides by the left denominator, then multiplying the both sides by the right denominator. DON’T THINK Cross multiply!! Forget it completely!!

  9. Eliminate one Denomiator at a time. * (4x + 5) (4x + 5) * (x + 1) * * (x + 1)

  10. Or: obtain a common denominator * (x + 1) (4x + 5) * (4x + 5) * * (x + 1) Multiply both sides by the common denominator

  11. Your Turn: 6. Solve 7. Solve 8. Solve

  12. What about this wrinkle? “multiply to eliminate the denominators one at a time” * x x * Now what? It’s a quadratic, solve the quadratic! put into standard form !!! Your turn: 9. solve

  13. Rational equations with 2 solutions. What values of ‘x’ are not allowed? Your turn:10. Eliminate the denominator.

  14. Your turn: 11. Solve

  15. Check for Extraneous solutions. Your Turn: 12. Solve. 13. Check to see if either one is extraneous.

  16. Multiply by the LCD • This is the most difficult method. • Determine what the LCD is. • Multiply both sides of the equation by the LCD. • Solve the resulting equation.

  17. Multiply both sides by the LCD!! What is the least common denominator? Factor the denominator 1. Look for what is common to each denominator. 3 2. What does the 1st denominatorneed to be common with the other two denominators? Needs a ‘2’ 3. What does the 2nd denominatorneed to be common with the other two denominators? Needs an ‘x’ 4. What does the 3rd denominatorneed to be common with the other two denominators? Needs an ‘2’

  18. Find the least common denominator 2 * 3x 2*3 3x 2 * * x The least common denominator is: 6x Multiply both sides by the LCD. 6x 6x

  19. Find the least common denominator The LCD is: 6x Multiply both sides by the LCD. 6x 6x Notice how I factored 6x so that it is easier to simplify. Wow ! x = 4

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