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Lesson 8-1: Multiplying and Dividing Rational Expressions

Lesson 8-1: Multiplying and Dividing Rational Expressions. Rational Expression. Definition: a ratio of two polynomial expressions. To Simplify A Rational Expression. 1. Make sure both the numerator and denominator are factored completely!!! 2. Look for common factors and cancel

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Lesson 8-1: Multiplying and Dividing Rational Expressions

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  1. Lesson 8-1: Multiplying and Dividing Rational Expressions

  2. Rational Expression • Definition: a ratio of two polynomial expressions

  3. To Simplify A Rational Expression 1. Make sure both the numerator and denominator are factored completely!!! 2. Look for common factors and cancel • Remember factors are things that are being multiplied you can NEVER cancel things that are being added or subtracted!!! 3. Find out what conditions make the expression undefined and state them.

  4. Examples: Simplify and state the values for x that result in the expression being undefined 1. 2.

  5. Examples Cont… Simplify 3. 4. 5.

  6. Operations with Rational Expressions To Multiply Rational Expressions: Factor and cancel where possible. Then multiply numerators and denominators Define x-values for which the expression is undefined To Divide Rational Expressions: Rewrite the problem as a multiplication problem with the first expression times the reciprocal of the second expression. Then factor and cancel where possible. Multiply numerators and denominators

  7. Examples: Simplify 6. 7. 8. 9.

  8. Polynomials in Numerator and Denominator • Rules are the same as before… 1. Make sure everything is factored completely 2. Cancel common factors 3. Simplify and define x values for which the expression is undefined.

  9. Examples: Simplify and define x values for which it is undefined 10. 11.

  10. Examples: 12. 13.

  11. Simplifying complex fractions • A complex fraction is a rational expression whose numerator and/or denominator contains a rational expression

  12. To simplify complex fractions • Same rules as before • Rewrite as multiplication with the reciprocal • Factor and cancel what you can • Simplify everything • Multiply to finish

  13. Examples: 14. 15.

  14. Lesson 8-2: Adding and Subtracting Rational Expressions

  15. Adding and Subtracting Rational Expressions • Finding Least Common Multiples and Least Common Denominators! • Use prime factorization • Example: Find the LCM of 6 and 4 • 6 = 2·3 • 4 = 22 • LCM= 22·3 = 12

  16. Find the LCM 1. 18r2s5, 24r3st2, and 15s3t 2. 15a2bc3, 16b5c2, 20a3c6 3. a2 – 6a + 9 and a2 + a -12 4. 2k3 – 5k2 – 12k and k3 – 8k2 +16k

  17. Add and Subtract Rational Expressions • Same as fractions… • To add two fractions we find the LCD, the same things is going to happen with rational expressions

  18. Examples: Simplify 5. 6. 7.

  19. 9. 8. 10.

  20. 11. 12.

  21. 13. 14.

  22. Lesson 8-3: Graphing Rational Functions

  23. Definitions • Continuity: graph may not be able to be traced without picking up pencil • Asymptote: a like that the graph of the function approaches, but never touches (this line is graphed as a dotted line) • Point discontinuity: a hole in the graph

  24. Vertical Asymptote How to find a Vertical Asymptote: x = the value that makes the rational expression undefined *Set the denominator of the rational expression equal to zero and solve.

  25. Point Discontinuity How to find point discontinuity: * Factor completely * Set any factor that cancels equal to zero and solve. Those are the x values that are points of discontinuity

  26. Graphing Rational Functions f(x) =

  27. Graphing Rational Functions f(x) =

  28. Graphing Rational Functions f(x) =

  29. Graphing Rational Functions f(x)=

  30. Graphing Rational Functions f(x) =

  31. Graphing Rational Functions f(x) =

  32. Lesson 8-4: Direct, Joint, and Inverse Variation

  33. Direct Variation y varies directly as x if there is a nonzero constant, k, such that y = kx *k is called the constant of variation • Plug in the two values you have and solve for the missing variable • Plug in that variable and the other given value to solve for the requested answer

  34. Example • If y varies directly as x and y = 12 when x = -3, find y when x = 16.

  35. Joint Variation • y varies jointly as x and z if there is a nonzero constant, k, such that y = kxz * Follow the same directions as before

  36. Example • Suppose y varies jointly as x and z. Find y when x = 8 and z = 3, if y = 16 when z = 2 and x = 5.

  37. Inverse Variation • y varies inversely as x if there is a nonzero constant, k, such that xy= k or y= k x

  38. Example • If y varies inversely as x and y = 18 when x = -3, find y when x = -11

  39. Lesson 8-6: Solving Rational Equations and Inequalities

  40. Let’s review some old skills • How do you find the LCM of two monomials • 8x2y3 and 18x5 * Why do we find LCM’s with rational expressions?

  41. Old Skills Cont… • What is it called when two fractions are equal to each other? • What process do we use to solve a problem like this?

  42. To solve a rational equation: 1. Make sure the problem is written as a proportion 2. Cross Multiply 3. Solve for x 4. Check our answer

  43. Examples • Solve

  44. Solve . Let’s put those old skills to new use…

  45. Solve . Check your solution.

  46. Examples • Solve

  47. Lesson 8-6: Day #2 Rational Inequalities

  48. Solving Rational Inequalities Step 1: State any excluded values (where the denominator of any fraction could equal zero) Step 2: Solve the related equation Step 3: Divide a numberline into intervals using answers from steps 1 and 2 to create intervals Step 4: Test a value in each interval to determine which values satisfy the inequality

  49. Examples • Solve

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