SECTION 5.1 Simplifying Rational Expressions Chapter 5 Rational Expressions, Equations, and Functions Section 5.1: Simplifying Rational Expressions Rational Expressions Rational Expressions Definition: Simplifying: MATH 1300 Fundamentals of Mathematics 297 CHAPTER 5 Rational Expressions, Equations, and Functions Example: Solution: 298 University of Houston Department of Mathematics SECTION 5.1 Simplifying Rational Expressions Additional Example 1: Solution: Additional Example 2: Solution: MATH 1300 Fundamentals of Mathematics 299 CHAPTER 5 Rational Expressions, Equations, and Functions Additional Example 3: Solution: Additional Example 4: 300 University of Houston Department of Mathematics SECTION 5.1 Simplifying Rational Expressions Solution: MATH 1300 Fundamentals of Mathematics 301 Exercise Set 5.1: Simplifying Rational Expressions 16. x3 x2 9 17. a 2 b2 ab 18. x 2 16 x4 19. 49 c 2 c 2 9c 18 20. x 2 11x 10 100 x 2 21. x 2 2 x 15 x 2 10 x 21 22. m2 m 20 m2 m 30 23. x2 5x 6 x 2 x 12 24. x 2 7 x 12 x 2 7 x 30 x y yx 25. x 2 8 x 12 x 2 13x 42 cd 10. d c 26. x 2 7 x 10 x 2 7 x 10 27. x 2 36 x 2 12 x 36 28. x2 8x 16 x2 16 29. 9 x 36 x2 4 x 7 x 2 14 x x2 10 x 2 30 x 5 x 2 10 x Simplify the following rational expressions. If the expression cannot be simplified any further, then simply rewrite the original expression. 1. 15 25 2. 30 36 3. 48 64 4. 26 39 5. 6. 7. 8. 9. 11. 60 x 2 y 5 48 x 5 y 3 49a 4 b9 56a 7 b10 5 x3 x y 10 x5 x y 8c 6 c d 2 12c c d 3 3 2 a b c d 6 b a 12. 12 x y w z 6 z w x y 4x 8 13. x2 302 7 14. x3 5 x 15 30. 15. x5 x 2 25 31. University of Houston Department of Mathematics Exercise Set 5.1: Simplifying Rational Expressions 32. 6 x2 8x 9 x3 12 x 2 48. x5 x 125 33. x2 7 x 6 8x2 8x 49. x3 27 x 2 3x 9 34. 4 x 2 20 x x2 4 x 5 50. x3 1 x2 x 1 35. 6 x 2 24 x 18 4 x 2 8 x 60 36. 5x2 10 x 40 10 x2 30 x 20 37. 4 x 2 17 x 15 5 x 2 13x 6 38. 4 x 2 8 x 21 8 x 2 24 x 14 39. 6 x2 5x 4 10 x 2 9 x 2 40. 15x 2 4 x 4 5x2 22 x 8 41. 8x2 30 x 7 16 x 2 1 42. 9 x 2 25 6 x 2 13x 5 43. m3 m2 m 1 m3 m m2 n n 44. ax ay bx by ax ay 2 x 2 y 45. xy 3x 2 y 6 yz 3z 5 y 15 46. ab 5a 2b 10 a 2 b 4b 5a 2 20 47. x3 8 x2 MATH 1300 Fundamentals of Mathematics 3 303 CHAPTER 5 Rational Expressions, Equations, and Functions Section 5.2: Multiplying and Dividing Rational Expressions Multiplication and Division Multiplication and Division Multiplication of Rational Expressions: To multiply two fractions, place the product of the numerators over the product of the denominators. Example: Solution: 304 University of Houston Department of Mathematics SECTION 5.2 Multiplying and Dividing Rational Expressions Division of Rational Expressions: Example: Solution: MATH 1300 Fundamentals of Mathematics 305 CHAPTER 5 Rational Expressions, Equations, and Functions Additional Example 1: Solution: Additional Example 2: 306 University of Houston Department of Mathematics SECTION 5.2 Multiplying and Dividing Rational Expressions Solution: Additional Example 3: MATH 1300 Fundamentals of Mathematics 307 CHAPTER 5 Rational Expressions, Equations, and Functions Solution: 308 University of Houston Department of Mathematics Exercise Set 5.2: Multiplying and Dividing Rational Expressions Multiply the following rational expressions and simplify. No answers should contain negative exponents. 16. ( x 2) 3 2 x 1. 6 14 7 18 17. ( x 5) 3x 2 5 x 2. 8 45 9 32 18. (3 x) 2x 1 x3 3. 10 2 5 19. ( x 4) 3 5 x 20 4. 12 5. ab4 c7 d 3 c 5 d 8 a 6 b9 21. (2 x 8) 3x 4 3 x 12 6. x5 y 6 wz 3 w3 z 8 x10 y 9 22. (3 x 3) 2x 2 4x 4 23. 7. m8 n 2 n 4t 6 p 6t 2 3 5 5 3 7 pt m mn 6 x 12 4 x 12 x 3 3x 6 x 7 6 x 24 2 x 8 5 x 35 8. x y a b 2 7 7 ab x y 24. 25. 6 x 10 3 5 x 15 9 x 26. 2x 4x 6 6 x 9 x2 x 27. x2 x 6 x2 6 x 5 x 2 3x 4 x 2 2 x 15 28. x 2 x 2 x 2 x 12 x 2 8x 15 x 2 9 x 14 29. x 2 3x 10 2 x 2 4 x x5 6 x2 24 x 30. 6 x 2 30 x x 2 4 x 21 x 2 x 6 40 x 8x 2 31. x 4 x2 9 3 x x 2 16 20. (4 x 28) 3 8 3 4 9. 2 x 2 10. 6 x 4 11. 12. 13. 8 2 x y a 5 b y 2 3 4 3 6 x5 5 2x x5 x3 x 3 x 10 x 6 5 x 1 x 6 x 2 14. ( x 1) 15. (7 x) x5 x2 x3 x 1 5 x x7 MATH 1300 Fundamentals of Mathematics 2 x7 309 Exercise Set 5.2: Multiplying and Dividing Rational Expressions 32. x 2 25 x 2 12 x 36 x6 x5 47. x3 x5 x 1 x 1 33. 2 x 2 9 x 10 x 2 7 x 12 x 2 5 x 6 2 x 2 3x 5 48. x 4 x3 x2 x2 34. x 2 2 x 8 3x 2 14 x 5 3x 2 16 x 5 x 2 x 20 49. 7 x 7 x2 1 21x 3x 35. ax bx ay by ax 7 x 2a 14 ax 7 x 3a 21 ax bx 2a 2b 50. 7 x4 x2 9 x 3 36. ac 2ad bc 2bd c2 d 2 ac ad bc bd 3ac 3ad bc bd 51. x2 1 x 1 x 6 3x 18 52. x 5x x2 4 x 2 5 15 37. 8 32 53. 5 10 2 x4 16 x 6 4 38. 25 5 54. x2 4 2 x x 5 25 x 2 25 39. 10 2 55. x2 9 x3 x2 1 x2 2 x 1 12 40. 6 7 56. 4 x2 9 2x 3 x 10 x 25 x 5 2 6 41. 3 57. x 2 3x 10 x 2 x 6 x 2 3x 28 x2 x 12 4 42. 40 5 58. x 2 4 x 4 x 2 8 x 20 x 2 6 x 16 x 2 9 x 8 x x4 z3 43. 2 7 5 y z y 59. 6 x 2 x 1 3x 2 2 x 1 6 x 2 5 x 1 3x 2 4 x 1 a 3 c 7 b5 c 9 44. 2 b4 a 60. 10 x 2 17 x 6 6 x 2 5 x 4 5x 2 4 x 12 3x 2 2 x 8 a 5b6 45. 2 5 a5 d 2 c d 61. am an bm bn am an 3bm 3bn am an bm bn am an 3bm 3bn x3 y 2 46. x z 6 w z 62. cx 2dx cy 2dy cx cy 5dx 5dy cx 5dx c 5d x 2 x 3xy 3 y Divide the following rational expressions and simplify. No answers should contain negative exponents. 4 5 310 2 University of Houston Department of Mathematics SECTION 5.3 Adding and Subtracting Rational Expressions Section 5.3: Adding and Subtracting Rational Expressions Addition and Subtraction Addition and Subtraction Addition and Subtraction of Rational Expressions with Like Denominators: Example: Perform the following operations. All results should be in simplified form. MATH 1300 Fundamentals of Mathematics 311 CHAPTER 5 Rational Expressions, Equations, and Functions Solution: Addition and Subtraction of Rational Expressions with Unlike Denominators: Example: 312 University of Houston Department of Mathematics SECTION 5.3 Adding and Subtracting Rational Expressions Solution: Additional Example 1: Perform the following operations. All results should be in simplified form. MATH 1300 Fundamentals of Mathematics 313 CHAPTER 5 Rational Expressions, Equations, and Functions Solution: Additional Example 2: Perform the addition. Give the result in simplified form. Solution: 314 University of Houston Department of Mathematics SECTION 5.3 Adding and Subtracting Rational Expressions Additional Example 3: Perform the subtraction. Give the result in simplified form. Solution: MATH 1300 Fundamentals of Mathematics 315 CHAPTER 5 Rational Expressions, Equations, and Functions Additional Example 4: Perform the subtraction. Give the result in simplified form. Solution: 316 University of Houston Department of Mathematics SECTION 5.3 Adding and Subtracting Rational Expressions Additional Example 5: Perform the following operations. Give all results in simplified form. MATH 1300 Fundamentals of Mathematics 317 CHAPTER 5 Rational Expressions, Equations, and Functions Solution: 318 University of Houston Department of Mathematics Exercise Set 5.3: Adding and Subtracting Rational Expressions Perform the indicated operations and simplify. (Whenever possible, write both the numerator and denominator of the answer in factored form.) 16. 1 2 x2 x2 1. 2x 3y 5 7 17. 6 2 x3 x7 2. 4a 2b 5 3 18. 7 4 x9 x2 3. 3 2 4a 9b 19. 5 x4 x 3 3 x 4. 7 5 2c 3c 20. x 2 x 5 x x5 5. 7 2 5 2 2 x y xy 21. 3 2 x5 6. 3 2 a 4 b7 a 5b 4 22. 4 5 x7 7. x8 x7 x5 x5 23. 7 2 x2 8. x 3 4x 6 x 1 x 1 24. 6 4 x3 9. 3x 2 2x 6 5 x 20 5 x 20 25. x4 2 x 1 x 3 2 x 3 10 x 9 10. 4x 3 4x 3 26. x3 1 x3 x3 2 3 11. x 1 x 5 27. x2 3 x x2 12. 5 6 x4 x7 28. x 4 x3 x5 13. 3 8 x x 1 29. x 1 1 x 1 2x 1 5 2 14. x x4 30. 2x 3 6 x x 1 3 4 15. x 1 x 2 31. x 3 x 1 x2 x4 MATH 1300 Fundamentals of Mathematics 319 Exercise Set 5.3: Adding and Subtracting Rational Expressions 32. x 1 x 2 x 3 x 1 33. x5 x2 x4 x3 34. x4 x2 x 1 x 1 35. 7 5 8 x 12 6 x 6 36. 5 2 12 x 6 10 x 40 37. 3 8 6 x x 1 x 2 38. 2 4 3 x3 x2 x 39. 5 320 4 x2 3 x2 2 x 8 40. 3x 2 5 x 2 x 2 3x 4 41. x 2 5 2 2 x 2x 8 x 2x x 4x 42. x 1 1 2 2 x 3x 18 x 6 x x 3x 43. x 4 2 x 2 10 x 24 x 2 12 x 32 x 2 14 x 48 44. x 2 3 x 2 7 x 12 x 2 4 x 3 x 2 5 x 4 2 2 University of Houston Department of Mathematics SECTION 5.4 Complex Fractions Section 5.4: Complex Fractions Simplifying Complex Fractions Simplifying Complex Fractions Definition: Simplifying: MATH 1300 Fundamentals of Mathematics 321 CHAPTER 5 Rational Expressions, Equations, and Functions Example: Solution: Method 1: 322 University of Houston Department of Mathematics SECTION 5.4 Complex Fractions Method 2: MATH 1300 Fundamentals of Mathematics 323 CHAPTER 5 Rational Expressions, Equations, and Functions Additional Example 1: Solution: Additional Example 2: Solution: 324 University of Houston Department of Mathematics SECTION 5.4 Complex Fractions Additional Example 3: Solution: MATH 1300 Fundamentals of Mathematics 325 CHAPTER 5 Rational Expressions, Equations, and Functions Additional Example 4: Solution: 326 University of Houston Department of Mathematics SECTION 5.4 Complex Fractions Additional Example 5: Solution: MATH 1300 Fundamentals of Mathematics 327 Exercise Set 5.4: Complex Fractions Simplify the following. No answers should contain negative exponents. 1. 2. 3. 7 12 5 8 10. 11. 6 7 2 3 5. 6. 7. 8. 9. 328 5 6 1 2 2 3 1 12. 4x y x4 5 y3 13. 12a b 4c 2 b7 2ab 2 c3 d 8a 3 c 5bd 4 3x 4 y 8 w6 z 5 9 x2 w 4z7 4 x3 yz 8x2 y5 5b3c 2d 10bd 2 3 3 4 1 2 2 5 14. 1 7 1 7 2 5 4. 5 1 6 2 3 2 5 3 1 4 1 2 2 5 8 4 2 3 15. x2 5 x3 10 16. x7 8 x 1 12 17. ab b ba ab 3 18. 19. x2 y x y xy x 2 7 x 12 8x x 2 x 20 6x4 University of Houston Department of Mathematics Exercise Set 5.4: Complex Fractions 20. 9 x5 x 6 x 16 18 x3 x 2 11x 24 21. x x 3 2 x x 3 2 22. a a 4 5 a a 3 4 23. x2 1 x 1 1 2 2x 24. 5 1 3x 3 25 x 2 x 25. 2 3 a b 5 4 a b 26. 7 2 x y 3 4 x y 2 6 x 1 9 x x x 27. 4 x 10 x x7 30. 6x x x2 4 1 x 2 x 1 31. 1 3 x3 x4 3 2 x 3 x 1 32. 2 5 x 1 x 2 3 2 x2 x 33. 15 x 12 x7 x 2 x2 34. For each of the following expressions, (a) Rewrite the expression so that it contains positive exponents rather than negative exponents. (b) Simplify the expression. 35. x1 x 1 36. 3 x 1 x 1 29. 2 3 x5 x5 2 2 x 25 MATH 1300 Fundamentals of Mathematics 1 37. x 1 y 1 x 1 y 1 38. c 1 d 1 c 2 d 2 39. x 2 y 2 x 1 y 1 x 28. 14 x 7 x6 x x9 329 Exercise Set 5.4: Complex Fractions 40. a 1 b 1 b 2 a 2 41. c 1 d 1 c 3 d 3 42. x 3 y 3 x 1 y 1 43. a 3 b 3 a 2 b 2 44. x 2 y 2 x 3 y 3 45. 1 1 1 x 1 46. 1 1 1 x 2 47. 4 48. 330 5 5 x 1 2 3 2 x 1 University of Houston Department of Mathematics SECTION 5.5 Solving Rational Equations Section 5.5: Solving Rational Equations Rational Equations Rational Equations Definition of a Rational Equation: Solving a Rational Equation: Example: Solution: MATH 1300 Fundamentals of Mathematics 331 CHAPTER 5 Rational Expressions, Equations, and Functions Example: Solution: 332 University of Houston Department of Mathematics SECTION 5.5 Solving Rational Equations MATH 1300 Fundamentals of Mathematics 333 CHAPTER 5 Rational Expressions, Equations, and Functions Extraneous Solutions: Example: Solution: 334 University of Houston Department of Mathematics SECTION 5.5 Solving Rational Equations Additional Example 1: Solution: MATH 1300 Fundamentals of Mathematics 335 CHAPTER 5 Rational Expressions, Equations, and Functions Additional Example 2: Solution: 336 University of Houston Department of Mathematics SECTION 5.5 Solving Rational Equations Additional Example 3: Solution: MATH 1300 Fundamentals of Mathematics 337 CHAPTER 5 Rational Expressions, Equations, and Functions 338 University of Houston Department of Mathematics SECTION 5.5 Solving Rational Equations Additional Example 4: Solution: MATH 1300 Fundamentals of Mathematics 339 Exercise Set 5.5: Solving Rational Equations Solve the following. Remember to identify any extraneous solutions. 3x 1 7 x5 1. 2x x 2 5 3 18. 3x 2 x7 2. 3a 2a 1 4 3 19. 7 1 x 9 3c 2c 22 2 5 20. 5 0 x 4 5x x 14 8 4 21. x5 1 x 7 x 12 5 x 3x 2 6 10 22. 11 x 1 x 3 x 10 6. 7 x 3x 5 8 20 23. 5 9 2 7 t 3 7. 4x 7 x 3 x5 x5 24. 3 12 3 x 1 5 8. 3x 4 x 8 x2 x2 25. 7 x8 1 9 x 1 9. x 5 2x 6 x 1 x 1 26. a2 1 1 a9 4 10. 3x 4 5 x 7 x6 x6 27. x7 2 3 x7 3 11. 2 7 3 5x 4 x 28. 2 t2 2 3 t 3 7 5 2 6x 4x 29. w 1 3 13 w 1 4 12 3 4 x2 30. x4 1 9 x 9 2 14 5 3 x7 31. 5 x3 7 3 x4 x4 2 0 x5 32. x 3 x3 x2 7 x2 3. 4. 5. 12. 13. 14. 15. 16. 340 17. 2 2 2 2 5x 0 x2 University of Houston Department of Mathematics Exercise Set 5.5: Solving Rational Equations 33. 4 1 8 x 5 3 3x 15 49. 4 1 1 x 4 x 1 34. 7 4 5 x 2 3x 6 3 50. 5 2 1 x4 x2 35. 3 2 1 4a 8 3a 6 36 51. 7 8 1 x5 x8 36. 5 1 7 3c 15 2c 10 12 52. 5 6 1 x7 x9 37. 3 1 7 x 5 x 3 x 2 2 x 15 53. x4 2 1 x 5 x 10 38. 2 1 4 x 1 x 2 x2 x 2 54. x2 1 1 x7 x3 39. 4 2 8 2 x 3 x 1 x 2x 3 55. 1 4 x 2 x 5 3x 2x 5 40. 7 2 10 2 x 4 x 5 x 9 x 20 56. 2 1 6x 3x 1 x 3x 1 41. 3 4 8 2 x2 x2 x 4 57. 4 3 3x 3x 2 x 1 x 1 42. 3 6 24 2 x 4 x 4 x 16 58. 5 2 x 2x 3 x 2x 3 43. 1 44. 1 6 x x2 12 1 1 x2 x 45. 2 7 4 x x2 46. 4 11 3 x2 x 47. 6 1 1 x4 x 48. 7 4 1 x x5 MATH 1300 Fundamentals of Mathematics 341 CHAPTER 5 Rational Expressions, Equations, and Functions Section 5.6: Rational Functions Working with Rational Functions Working with Rational Functions Definition of a Rational Function: Domain of a Rational Function: Example: 342 University of Houston Department of Mathematics SECTION 5.6 Rational Functions Solution: MATH 1300 Fundamentals of Mathematics 343 CHAPTER 5 Rational Expressions, Equations, and Functions Graph of a Rational Function: Example: Solution: 344 University of Houston Department of Mathematics SECTION 5.6 Rational Functions The graph of the function is shown below, labeled with the information from parts (b)-(d). MATH 1300 Fundamentals of Mathematics 345 CHAPTER 5 Rational Expressions, Equations, and Functions Vertical Asymptotes: 346 University of Houston Department of Mathematics SECTION 5.6 Rational Functions Finding Vertical Asymptotes Example: Solution: MATH 1300 Fundamentals of Mathematics 347 CHAPTER 5 Rational Expressions, Equations, and Functions Horizontal Asymptotes: 348 University of Houston Department of Mathematics SECTION 5.6 Rational Functions Additional Example 1: Solution: f x 0 x3 0 x 1 MATH 1300 Fundamentals of Mathematics 349 CHAPTER 5 Rational Expressions, Equations, and Functions 350 University of Houston Department of Mathematics SECTION 5.6 Rational Functions Additional Example 2: Solution: Additional Example 3: MATH 1300 Fundamentals of Mathematics 351 CHAPTER 5 Rational Expressions, Equations, and Functions Solution: 352 University of Houston Department of Mathematics SECTION 5.6 Rational Functions MATH 1300 Fundamentals of Mathematics 353 Exercise Set 5.6: Rational Functions Find the indicated function values. If undefined, state “Undefined.” 1. If f ( x ) (a) 2. 3. 4. (a) 5. f 13 (c) f 15 (c) f 54 3x 2 , find x7 (b) f (3) 2x 7 , find x6 (b) f (4) f (0) Graph I: Graph II: (c) 2 , find x2 x 6 (c) f (2) (b) f (0) x 1 If f ( x) 2 , find x 2x 1 (a) f (4) (b) f (0) (c) y f 34 y x x If f ( x) (a) 6. (b) f (5) f (0) If f ( x ) (c) 5 , find x5 f (0) If f ( x ) (a) (b) f (1) f (0) If f ( x) (a) x , find x3 The graph of each of the following functions has a horizontal asymptote at y 1 . (You will learn how to find horizontal asymptotes in a later mathematics course.) For each function, (a) Find the domain of the function and express it as an inequality. (b) Write the equation of the vertical asymptote(s) of the function. (c) Find the x- and y-intercept(s) of the function, if they exist. If an intercept does not exist, state “None.” (d) Find f (1) and f (1) . (e) Based on the features from (a)-(d), match the function with its corresponding graph, using the choices (Graphs I-IV) below. f (5) Graph III: Graph IV: f (1) y y x x 7. x , find x 121 f (3) (b) f (0) (c) 1 , find x 2 5 x 14 (a) f (0) (b) f (1) (c) If f ( x) (a) 8. 9. 2 f (12) If x3 , find x 11x 28 (b) f (4) (c) f (3) If f ( x) (a) (a) f (7) 2 x5 , find x x 12 (b) f (2) (c) f (0) 10. If f ( x ) 354 11. f ( x) x4 x3 12. f ( x) x6 x2 13. f ( x) x6 x3 14. f ( x) x4 x2 f (0) 2 f (5) University of Houston Department of Mathematics Exercise Set 5.6: Rational Functions The graph of each of the following functions has a horizontal asymptote at y 0 . (You will learn how to find horizontal asymptotes in a later mathematics course.) For each function, (a) Find the domain of the function and express it as an inequality. (b) Write the equation of the vertical asymptote(s) of the function. (c) Find the x- and y-intercept(s) of the function, if they exist. If an intercept does not exist, state “None.” (d) Find f (1) and f (1) . (e) Based on the features from (a)-(d), match the function with its corresponding graph, using the choices (Graphs I-IV) below. Graph I: 19. If f ( x) 10 x5 20. f ( x) 12 x3 21. f ( x) x6 x2 22. f ( x ) x 8 x 23. f ( x) x3 x 24. f ( x) 4 x x 1 25. f ( x) 9 x x2 9 26. f ( x) x 8 x 2 16 Graph II: y y x x For each of the following functions, (a) Find the domain of the function and express it as an inequality. Then write the domain of the function in interval notation. (b) Write the equation of the vertical asymptote(s) of the function. (c) Find the x- and y- intercept(s) of the function. If an intercept does not exist, state “None." Graph III: Graph IV: y y x 15. f ( x) 16. f ( x ) x 27. f ( x) 24 x 8 x 12 2 4 x2 28. f ( x) 2x x x 20 8 x 29. f ( x) x5 x 2x 1 x 8 x2 5x 4 2 2 17. f ( x) 4 x 30. f ( x) 18. f ( x) 8 x2 31. f ( x) 32. f ( x) MATH 1300 Fundamentals of Mathematics 4 x2 8x x4 x 6x 2 355 Exercise Set 5.6: Rational Functions 356 33. f ( x) x2 10 x 25 5 x 34. f ( x) x2 7 x 18 5x 35. f ( x) 2x x 25 36. f ( x) x 1 x 2 16 37. f ( x) x2 5x 14 5x 7 38. f ( x) 9 x2 1 3x 2 39. f ( x) 25x 2 36 x2 5x 4 40. f ( x) x2 7 x 6 x 2 5 x 24 2 University of Houston Department of Mathematics