Review Exercises

Determine whether the statement is true or false.

  1. 1. If f(x)=(x+a)(x+b)(xc), then f(b)=0. [4.3]

  2. 2. The graph of a rational function never crosses a vertical asymptote. [4.5]

  3. 3. For the function g(x)=x48x29, the only possible rational zeros are 1, −1, 3, and −3. [4.4]

  4. 4. The graph of P(x)=x6x8 has at most 6 x-intercepts. [4.2]

  5. 5. The domain of the function

    f(x)=x4(x+2)(x3)

    is (, 2)(3, ). [4.5]

Determine the leading term, the leading coefficient, and the degree of the polynomial. Then classify the polynomial function as constant, linear, quadratic, cubic, or quartic. [4.1]

  1. 6. f(x)=7x25+0.45x43x3

  2. 7. h(x)=25

  3. 8. g(x)=60.5x

  4. 9. f(x)=13 x32x+3

Use the leading-term test to describe the end behavior of the graph of the function. [4.1]

  1. 10. f(x)= 12 x4+3x2+x6

  2. 11. f(x)=x5+2x3x2+5x+4

Find the zeros of the polynomial function and state the multiplicity of each. [4.1]

  1. 12. g(x)=(x23)(x+2)3(x5)2

  2. 13. f(x)=x426x2+25

  3. 14. h(x)=x3+4x29x36

  4. 15. Interest Compounded Annually. When P dollars is invested at interest rate i, compounded annually, for t years, the investment grows to A dollars, where

    A=P (1+i)t.
    1. Find the interest rate i if $6250 grows to $6760 in 2 years. [4.1]

    2. Find the interest rate i if $1,000,000 grows to $1,215,506.25 in 4 years. [4.1]

Sketch the graph of the polynomial function.

  1. 16. f(x)=x4+2x3 [4.2]

  2. 17. g(x)=(x1)3(x+2)2 [4.2]

  3. 18. h(x)=x3+3x2x3 [4.2]

  4. 19. f(x)=x45x3+6x2+4x8 [4.2], [4.3], [4.4]

  5. 20. g(x)=2x3+7x214x+5 [4.2], [4.4]

Using the intermediate value theorem, determine, if possible, whether the function f has a zero between a and b. [4.2]

  1. 21. f(x)=4x25x3; a=1, b=2

  2. 22. f(x)=x34x2+12x+2; a=1, b=1

In each of the following, a polynomial P(x) and a divisor d(x) are given. Use long division to find the quotient Q(x) and the remainder R(x) when P(x) is divided by d(x). Express P(x) in the form d(x)Q(x)+R(x). [4.3]

  1. 23. P(x)=6x32x2+4x1,d(x)=x3

  2. 24. P(x)=x42x3+x+5,d(x)=x+1

Use synthetic division to find the quotient and the remainder. [4.3]

  1. 25. (x3+2x213x+10)÷(x5)

  2. 26. (x4+3x3+3x2+3x+2)÷(x+2)

  3. 27. (x52x)÷(x+1)

Use synthetic division to find the indicated function value. [4.3]

  1. 28. f(x)=x3+2x213x+10; f(2)

  2. 29. f(x)=x416; f(2)

  3. 30. f(x)=x54x4+x3x2+2x100; f(10)

Using synthetic division, determine whether the given numbers are zeros of the polynomial function. [4.3]

  1. 31. i, 5; f(x)=x35x2+x5

  2. 32. 1, 2; f(x)=x44x33x2+14x8

  3. 33. 13, 1; f(x)=x343 x253x+23

  4. 34. 2, 3; f(x)=x45x2+6

Factor the polynomial f(x). Then solve the equation f(x)=0. [4.3], [4.4]

  1. 35. f(x)=x3+2x27x+4

  2. 36. f(x)=x3+4x23x18

  3. 37. f(x)=x44x321x2+100x100

  4. 38. f(x)=x43x2+2

Find a polynomial function of degree 3 with the given numbers as zeros. [4.4]

  1. 39. 4, 1, 2

  2. 40. 3, 1i, 1+i

  3. 41. 12, 12, 1+2

  4. 42. Find a polynomial function of degree 4 with −5 as a zero of multiplicity 3 and 12 as a zero of multiplicity 1. [4.4]

  5. 43. Find a polynomial function of degree 5 with −3 as a zero of multiplicity 2, 2 as a zero of multiplicity 1, and 0 as a zero of multiplicity 2. [4.4]

Suppose that a polynomial function of degree 5 with rational coefficients has the given zeros. Find the other zero(s). [4.4]

  1. 44.  23, 5, i

  2. 45. 0, 1+3, 3

  3. 46. 2, 12, 1, 2

Find a polynomial function of lowest degree with rational coefficients and the following as some of its zeros. [4.4]

  1. 47. 11

  2. 48. i, 6

  3. 49. 1, 4, 1+i

  4. 50. 5, 2i

  5. 51. 13, 0, 3

List all possible rational zeros. [4.4]

  1. 52. h(x)=4x52x3+6x12

  2. 53. g(x)=3x4x3+5x2x+1

  3. 54. f(x)=x32x2+x24

For each polynomial function, (a) find the rational zeros and then the other zeros; that is, solve f(x)=0; and (b) factor f(x) into linear factors. [4.4]

  1. 55. f(x)=3x5+2x425x328x2+12x

  2. 56. f(x)=x32x23x+6

  3. 57. f(x)=x46x3+9x2+6x10

  4. 58. f(x)=x3+3x211x5

  5. 59. f(x)=3x38x2+7x2

  6. 60. f(x)=x58x4+20x38x232x+32

  7. 61. f(x)=x6+x528x416x3+192x2

  8. 62. f(x)=2x513x4+32x338x2+22x5

What does Descartes’ rule of signs tell you about the number of positive real zeros and the number of negative real zeros of each of the following polynomial functions? [4.4]

  1. 63. f(x)=2x67x3+x2x

  2. 64. h(x)=x8+6x5x3+2x2

  3. 65. g(x)=5x54x2+x1

Graph the function. Be sure to label all the asymptotes. List the domain and the x- and y-intercepts. [4.5]

  1. 66. f(x)=x25x+2

  2. 67. f(x)=5(x2)2

  3. 68. f(x)=x2+x6x2x20

  4. 69. f(x)=x2x22x15

In Exercises 70 and 71, find a rational function that satisfies the given conditions. Answers may vary, but try to give the simplest answer possible. [4.5]

  1. 70. Vertical asymptotes x=2, x=3

  2. 71. Vertical asymptotes x=2, x=3; horizontal asymptote y=4; x-intercept (−3, 0)

  3. 72. Medical Dosage. The function

    N(t)=0.7t+20008t+9, t5,

    gives the body concentration N(t), in parts per million, of a certain dosage of medication after time t, in hours.

    1. Find the horizontal asymptote of the graph and complete the following:

      N(t) as t.
      [4.5]
    2. Explain the meaning of the answer to part (a) in terms of the application. [4.5]

Solve. [4.6]

  1. 73. x29<0

  2. 74. 2x2>3x+2

  3. 75. (1x)(x+4)(x2)0

  4. 76. x2x+3<4

  5. 77. Height of a Rocket. The function

    S(t)=16t2+80t+224

    gives the height S, in feet, of a model rocket launched with a velocity of 80 ft/sec from a hill that is 224 ft high, where t is the time, in seconds.

    1. Determine when the rocket reaches the ground. [4.1]

    2. On what interval is the height greater than 320 ft? [4.1], [4.6]

  6. 78. Population Growth. The population P, in thousands, of Novi is given by

    P(t)=8000t4t2+10, 

    where t is the time, in months. Find the interval on which the population was 400,000 or greater. [4.6]

  7. 79. Which of the following is the domain of the function

    g(x)=x2+2x3x25x+6?
    [4.5]
    1. (, 2)(2, 3)(3, )

    2. (, 3)(3, 1)(1, )

    3. (, 2)(3, )

    4. (, 3)(1, )

  8. 80. Which of the following lists the vertical asymptotes of the function

    f(x)=x4(x+1)(x2)(x+4)?
    [4.5]
    1. x=1, x=2, and x=4

    2. x=1, x=2, x=4, and x=4

    3. x=1, x=2, and x=4

    4. x=4

  9. 81. The graph of f(x)=12x4+x3+1 is which of the following? [4.2]

Synthesis

Solve.

  1. 82. x252x  [4.6]

  2. 83. |11x2|<3 [4.6]

  3. 84. x42x3+3x22x+2=0 [4.4]

  4. 85. (x2)3<0 [4.6]

  5. 86. Express x31 as a product of linear factors. [4.4]

  6. 87. Find k such that x+3 is a factor of x3+kx2+kx15. [4.3]

  7. 88. When x24x+3k is divided by x+5, the remainder is 33. Find the value of k. [4.3]

Find the domain of the function. [4.5]

  1. 89. f(x)=x2+3x10

  2. 90. f(x)=x23.1x+2.2+1.75

  3. 91. f(x)=15|7x+2|

Collaborative Discussion and Writing

  1. 92. Explain the difference between a polynomial function and a rational function. [4.1], [4.5]

  2. 93. Is it possible for a third-degree polynomial with rational coefficients to have no real zeros? Why or why not? [4.4]

  3. 94. Explain and contrast the three types of asymptotes considered for rational functions. [4.5]

  4. 95. If P(x) is an even function, and by Descartes’ rule of signs, P(x) has one positive real zero, how many negative real zeros does P(x) have? Explain. [4.4]

  5. 96. Explain why the graph of a rational function cannot have both a horizontal asymptote and an oblique asymptote. [4.5]

  6. 97. Under what circumstances would a quadratic inequality have a solution set that is a closed interval? [4.6]

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