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13.1.12: Chapter 12

  • Page ID
    117747
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    Be Prepared

    12.1

    5, 7, 9, 11

    12.2

    −1 , 1 , −1 , 1 −1 , 1 , −1 , 1

    12.3

    20

    12.4

    3, 7, 11, 15

    12.5

    ( 5 , 2 ) ( 5 , 2 )

    12.6

    654

    12.7

    3 4 3 4

    12.8

    81; 116116

    12.9

    12; 36; 108

    12.10

    35

    12.11

    9 x 2 + 30 x + 25 9 x 2 + 30 x + 25

    12.12

    x 2 2 x y + y 2 x 2 2 x y + y 2

    Try It

    12.1

    −1 , 2 , 5 , 8 , 11 −1 , 2 , 5 , 8 , 11

    12.2

    −3 , −1 , 1 , 3 , 5 −3 , −1 , 1 , 3 , 5

    12.3

    7 , 13 , 31 , 85 , 247 7 , 13 , 31 , 85 , 247

    12.4

    −3 , −1 , 3 , 11 , 27 −3 , −1 , 3 , 11 , 27

    12.5

    −1 , 4 , −9 , 16 , −25 −1 , 4 , −9 , 16 , −25

    12.6

    1 , −8 , 27 , −64 , 125 1 , −8 , 27 , −64 , 125

    12.7

    a n = 3 n a n = 3 n

    12.8

    a n = 5 n a n = 5 n

    12.9

    a n = ( −1 ) n 3 n a n = ( −1 ) n 3 n

    12.10

    a n = ( −1 ) n + 1 n 2 a n = ( −1 ) n + 1 n 2

    12.11

    a n = 1 2 n a n = 1 2 n

    12.12

    a n = 1 n 2 a n = 1 n 2

    12.13

    2 , 1 , 1 3 , 1 12 , 1 60 2 , 1 , 1 3 , 1 12 , 1 60

    12.14

    3 , 3 2 , 1 2 , 1 8 , 1 40 3 , 3 2 , 1 2 , 1 8 , 1 40

    12.15

    1 2 , 1 6 , 1 12 , 1 20 , 1 30 1 2 , 1 6 , 1 12 , 1 20 , 1 30

    12.16

    1 2 , 1 3 , 1 4 , 1 5 , 1 6 1 2 , 1 3 , 1 4 , 1 5 , 1 6

    12.17

    45

    12.18

    60

    12.19

    16 3 16 3

    12.20

    8

    12.21

    n = 1 5 1 2 n n = 1 5 1 2 n

    12.22

    n = 1 5 1 n 2 n = 1 5 1 n 2

    12.23

    n = 1 5 ( −1 ) n + 1 n 2 n = 1 5 ( −1 ) n + 1 n 2

    12.24

    n = 1 5 ( −1 ) n 2 n n = 1 5 ( −1 ) n 2 n

    12.25

    The sequence is arithmetic with common difference d=11d=11. The sequence is arithmetic with common difference d=−6d=−6.
    The sequence is not arithmetic as all the differences between the consecutive terms are not the same.

    12.26

    The sequence is not arithmetic as all the differences between the consecutive terms are not the same. The sequence is arithmetic with common difference d=2.d=2.
    The sequence is arithmetic with common difference d=−5.d=−5.

    12.27

    7 , 3 , −1 , −5 , −9 , 7 , 3 , −1 , −5 , −9 ,

    12.28

    11 , 3 , −5 , −13 , −21 , 11 , 3 , −5 , −13 , −21 ,

    12.29

    241

    12.30

    −106 −106

    12.31

    a11=2.a11=2. The general term is an=−3n+35.an=−3n+35.

    12.32

    a19=−55.a19=−55. The general term is an=−4n+21.an=−4n+21.

    12.33

    a1=5,a1=5,d=4.d=4. The general term is an=4n+1.an=4n+1.

    12.34

    a1=8,a1=8,d=−3.d=−3. The general term is an=−3n+11.an=−3n+11.

    12.35

    1,890

    12.36

    1,515

    12.37

    2,300

    12.38

    5,250

    12.39

    2,670

    12.40

    3,045

    12.41

    The sequence is geometric with common ratio r=3.r=3. The sequence is geometric with common ratio r=14.r=14. The sequence is not geometric. There is no common ratio.

    12.42

    The sequence is not geometric. There is no common ratio. The sequence is geometric with common ratio r=2.r=2. The sequence is geometric with common ratio r=12.r=12.

    12.43

    7 , −21 , 63 , −189 , 567 7 , −21 , 63 , −189 , 567

    12.44

    6 , −24 , 96 , −384 , 1536 6 , −24 , 96 , −384 , 1536

    12.45

    1 6,561 1 6,561

    12.46

    1 16,384 1 16,384

    12.47

    a9=39,366.a9=39,366. The general term is an=6(3)n1.an=6(3)n1.

    12.48

    a11=7,168.a11=7,168. The general term is an=7(2)n1.an=7(2)n1.

    12.49

    3,145,725 3,145,725

    12.50

    10,460,353,200 10,460,353,200

    12.51

    393,204 393,204

    12.52

    10,230 10,230

    12.53

    96

    12.54

    256 3 256 3

    12.55

    4 9 4 9

    12.56

    8 9 8 9

    12.57

    $ 10,000 $ 10,000

    12.58

    $ 3 , 333.33 $ 3 , 333.33

    12.59

    $ 88,868.36 $ 88,868.36

    12.60

    $ 698,201.57 $ 698,201.57

    12.61

    x 5 + 5 x 4 y + 10 x 3 y 2 + 10 x 2 y 3 x 5 + 5 x 4 y + 10 x 3 y 2 + 10 x 2 y 3
    + 5 x y 4 + y 5 + 5 x y 4 + y 5

    12.62

    p 7 + 7 p 6 q + 21 p 5 q 2 + 35 p 4 q 3 p 7 + 7 p 6 q + 21 p 5 q 2 + 35 p 4 q 3
    + 35 p 3 q 4 + 21 p 2 q 5 + 7 p q 6 + q 7 + 35 p 3 q 4 + 21 p 2 q 5 + 7 p q 6 + q 7

    12.63

    x 4 + 8 x 3 + 24 x 2 + 32 x + 16 x 4 + 8 x 3 + 24 x 2 + 32 x + 16

    12.64

    x 6 + 6 x 5 + 15 x 4 + 20 x 3 + 15 x 2 x 6 + 6 x 5 + 15 x 4 + 20 x 3 + 15 x 2
    + 6 x + 1 + 6 x + 1

    12.65

    16 x 4 96 x 3 + 216 x 2 216 x + 81 16 x 4 96 x 3 + 216 x 2 216 x + 81

    12.66

    64 x 6 192 x 5 + 240 x 4 160 x 3 64 x 6 192 x 5 + 240 x 4 160 x 3
    + 60 x 2 12 x + 1 + 60 x 2 12 x + 1

    12.67

    6 1 1 35

    12.68

    2 1 1 6

    12.69

    x 5 + 5 x 4 y + 10 x 3 y 2 + 10 x 2 y 3 x 5 + 5 x 4 y + 10 x 3 y 2 + 10 x 2 y 3
    + 5 x y 4 + y 5 + 5 x y 4 + y 5

    12.70

    m 6 + 6 m 5 n + 15 m 4 n 2 + 20 m 3 n 3 m 6 + 6 m 5 n + 15 m 4 n 2 + 20 m 3 n 3
    + 15 m 2 n 4 + 6 m n 5 + n 6 + 15 m 2 n 4 + 6 m n 5 + n 6

    12.71

    x 5 15 x 4 + 90 x 3 270 x 2 x 5 15 x 4 + 90 x 3 270 x 2
    + 405 x 243 + 405 x 243

    12.72

    y 6 6 y 5 + 15 y 4 20 y 3 + 15 y 2 y 6 6 y 5 + 15 y 4 20 y 3 + 15 y 2
    6 y + 1 6 y + 1

    12.73

    243 x 5 810 x 4 y + 1080 x 3 y 2 243 x 5 810 x 4 y + 1080 x 3 y 2
    720 x 2 y 3 + 240 x y 4 32 y 5 720 x 2 y 3 + 240 x y 4 32 y 5

    12.74

    256 x 4 768 x 3 y + 864 x 2 y 2 256 x 4 768 x 3 y + 864 x 2 y 2
    432 x y 3 + 81 y 4 432 x y 3 + 81 y 4

    12.75

    15 x 4 y 2 15 x 4 y 2

    12.76

    70 a 4 b 4 70 a 4 b 4

    12.77

    3,584

    12.78

    280

    Section 12.1 Exercises

    1.

    −5 , −3 , −1 , 1 , 3 −5 , −3 , −1 , 1 , 3

    3.

    4 , 7 , 10 , 13 , 16 4 , 7 , 10 , 13 , 16

    5.

    5 , 7 , 11 , 19 , 35 5 , 7 , 11 , 19 , 35

    7.

    1 , 5 , 21 , 73 , 233 1 , 5 , 21 , 73 , 233

    9.

    2 , 1 , 8 9 , 1 , 32 25 2 , 1 , 8 9 , 1 , 32 25

    11.

    1 , 3 2 , 5 4 , 7 8 , 9 16 1 , 3 2 , 5 4 , 7 8 , 9 16

    13.

    −2 , 4 , −6 , 8 , −10 −2 , 4 , −6 , 8 , −10

    15.

    1 , −4 , 9 , −16 , 25 1 , −4 , 9 , −16 , 25

    17.

    1 , 1 4 , 1 9 , 1 16 , 1 25 1 , 1 4 , 1 9 , 1 16 , 1 25

    19.

    a n = 8 n a n = 8 n

    21.

    a n = n + 5 a n = n + 5

    23.

    a n = e n + 2 a n = e n + 2

    25.

    a n = ( −1 ) n 5 n a n = ( −1 ) n 5 n

    27.

    a n = ( −1 ) n n 3 a n = ( −1 ) n n 3

    29.

    a n = ( −1 ) n 2 n a n = ( −1 ) n 2 n

    31.

    a n = 1 4 n a n = 1 4 n

    33.

    a n = n n + 1 a n = n n + 1

    35.

    a n = 5 2 n a n = 5 2 n

    37.

    4 , 2 , 2 3 , 1 6 , 1 30 4 , 2 , 2 3 , 1 6 , 1 30

    39.

    3 , 6 , 18 , 72 , 360 3 , 6 , 18 , 72 , 360

    41.

    2 , 24 , 720 , 40320 , 3628800 2 , 24 , 720 , 40320 , 3628800

    43.

    1 , 1 2 , 1 3 , 1 4 , 1 5 1 , 1 2 , 1 3 , 1 4 , 1 5

    45.

    1 , 1 2 , 2 3 , 3 2 , 24 5 1 , 1 2 , 2 3 , 3 2 , 24 5

    47.

    2 , 3 2 , 8 3 , 15 2 , 144 5 2 , 3 2 , 8 3 , 15 2 , 144 5

    49.

    1 + 4 + 9 + 16 + 25 = 55 1 + 4 + 9 + 16 + 25 = 55

    51.

    5 + 7 + 9 + 11 + 13 + 15 = 60 5 + 7 + 9 + 11 + 13 + 15 = 60

    53.

    2 + 4 + 8 + 16 = 30 2 + 4 + 8 + 16 = 30

    55.

    4 1 + 4 1 + 4 2 + 4 6 = 32 3 = 10 2 3 4 1 + 4 1 + 4 2 + 4 6 = 32 3 = 10 2 3

    57.

    2 + 6 + 12 + 20 + 30 = 70 2 + 6 + 12 + 20 + 30 = 70

    59.

    1 2 + 2 3 + 3 4 + 4 5 + 5 6 = 71 20 1 2 + 2 3 + 3 4 + 4 5 + 5 6 = 71 20

    61.

    n = 1 5 1 3 n n = 1 5 1 3 n

    63.

    n = 1 5 1 n 3 n = 1 5 1 n 3

    65.

    n = 1 5 2 n n = 1 5 2 n

    67.

    n = 1 5 ( −1 ) n + 1 3 n n = 1 5 ( −1 ) n + 1 3 n

    69.

    n = 1 10 ( −1 ) n 2 n n = 1 10 ( −1 ) n 2 n

    71.

    n = 1 7 ( 2 n + 12 ) n = 1 7 ( 2 n + 12 )

    73.

    Answers will vary.

    75.

    Answers will vary.

    Section 12.2 Exercises

    77.

    The sequence is arithmetic with common difference d=8.d=8.

    79.

    The sequence is not arithmetic.

    81.

    The sequence is arithmetic with common difference d=−3.d=−3.

    83.

    11 , 18 , 25 , 32 , 39 11 , 18 , 25 , 32 , 39

    85.

    −7 , −3 , 1 , 5 , 9 −7 , −3 , 1 , 5 , 9

    87.

    14 , 5 , −4 , −13 , −22 14 , 5 , −4 , −13 , −22

    89.

    163 163

    91.

    131 131

    93.

    −79 −79

    95.

    a20=−34.a20=−34. The general term is an=−2n+6.an=−2n+6.

    97.

    a11=59.a11=59. The general term is an=5n+4.an=5n+4.

    99.

    a8=−13.a8=−13. The general term is an=−5n+27.an=−5n+27.

    101.

    a1=11,a1=11,d=3.d=3. The general term is an=3n+8.an=3n+8.

    103.

    a1=21,a1=21,d=−8.d=−8. The general term is an=−8n+29.an=−8n+29.

    105.

    a1=−15,a1=−15,d=3.d=3. The general term is an=3n18.an=3n18.

    107.

    1,635

    109.

    −1 , 065 −1 , 065

    111.

    360

    113.

    6,325

    115.

    –3,575

    117.

    6,280

    119.

    4,125

    121.

    −3,850 −3,850

    123.

    Answers will vary.

    125.

    Answers will vary.

    Section 12.3 Exercises

    127.

    The sequence is geometric with common ratio r=4.r=4.

    129.

    The sequence is geometric with common ratio r=12.r=12.

    131.

    The sequence is geometric with a common ratio r=−2.r=−2.

    133.

    The sequence is geometric with common ratio r=12.r=12.

    135.

    The sequence is arithmetic with common difference d=5.d=5.

    137.

    The sequence is geometric with common ratio r=12.r=12.

    139.

    4 , 12 , 36 , 108 , 324 4 , 12 , 36 , 108 , 324

    141.

    −4 , 8 , −16 , 32 , −64 −4 , 8 , −16 , 32 , −64

    143.

    27 , 9 , 3 , 1 , 1 3 27 , 9 , 3 , 1 , 1 3

    145.

    472,392 472,392

    147.

    3,072

    149.

    0.0001 0.0001

    151.

    a9=2,304.a9=2,304. The general term is an=9(2)n1.an=9(2)n1.

    153.

    a15=219,683.a15=219,683. The general term is an=−486(13)n1.an=−486(13)n1.

    155.

    a10=0.000000001.a10=0.000000001. The general term is an=(0.1)n1.an=(0.1)n1.

    157.

    57,395,624 57,395,624

    159.

    −65,538 −65,538

    161.

    7,174,453 59,049 121.5 7,174,453 59,049 121.5

    163.

    65,534 65,534

    165.

    4088 4088

    167.

    29,524 6561 4.5 29,524 6561 4.5

    169.

    3 2 3 2

    171.

    9 2 9 2

    173.

    no sum as r1r1

    175.

    2,048

    177.

    1 3 1 3

    179.

    7 9 7 9

    181.

    5 11 5 11

    183.

    $6666.67$6666.67 $4000$4000 $15,000$15,000 $7500$7500

    185.

    $ 295,581.88 $ 295,581.88

    187.

    $ 14,234.10 $ 14,234.10

    189.

    Answers will vary.

    191.

    Answers will vary.

    Section 12.4 Exercises

    193.

    a 8 + 8 a 7 b + 28 a 6 b 2 + 56 a 5 b 3 a 8 + 8 a 7 b + 28 a 6 b 2 + 56 a 5 b 3
    + 70 a 4 b 4 + 56 a 3 b 5 + 28 a 2 b 6 + 70 a 4 b 4 + 56 a 3 b 5 + 28 a 2 b 6
    + 8 a b 7 + b 8 + 8 a b 7 + b 8

    195.

    p 9 + 9 p 8 q + 36 p 7 q 2 + 84 p 6 q 3 p 9 + 9 p 8 q + 36 p 7 q 2 + 84 p 6 q 3
    + 126 p 5 q 4 + 126 p 4 q 5 + 84 p 3 q 6 + 126 p 5 q 4 + 126 p 4 q 5 + 84 p 3 q 6
    + 36 p 2 q 7 + 9 p q 8 + q 9 + 36 p 2 q 7 + 9 p q 8 + q 9

    197.

    a 6 6 a 5 b + 15 a 4 b 2 20 a 3 b 3 a 6 6 a 5 b + 15 a 4 b 2 20 a 3 b 3
    + 15 a 2 b 4 6 a b 5 + b 6 + 15 a 2 b 4 6 a b 5 + b 6

    199.

    x 3 + 15 x 2 + 75 x + 125 x 3 + 15 x 2 + 75 x + 125

    201.

    y 7 + 7 y 6 + 21 y 5 + 35 y 4 + 35 y 3 y 7 + 7 y 6 + 21 y 5 + 35 y 4 + 35 y 3
    + 21 y 2 + 7 y + 1 + 21 y 2 + 7 y + 1

    203.

    z 6 12 z 5 + 60 z 4 160 z 3 + 240 z 2 z 6 12 z 5 + 60 z 4 160 z 3 + 240 z 2
    192 z + 64 192 z + 64

    205.

    243 x 5 405 x 4 + 270 x 3 90 x 2 243 x 5 405 x 4 + 270 x 3 90 x 2
    + 15 x 1 + 15 x 1

    207.

    27 x 3 135 x 2 + 225 x 125 27 x 3 135 x 2 + 225 x 125

    209.

    27 x 3 + 135 x 2 y + 225 x y 2 + 125 y 3 27 x 3 + 135 x 2 y + 225 x y 2 + 125 y 3

    211.

    7 1 1 45

    213.

    4 1 1 55

    215.

    m 5 + 5 m 4 n + 10 m 3 n 2 + 10 m 2 n 3 m 5 + 5 m 4 n + 10 m 3 n 2 + 10 m 2 n 3
    + 5 m n 4 + n 5 + 5 m n 4 + n 5

    217.

    s 7 + 7 s 6 t + 21 s 5 t 2 + 35 s 4 t 3 s 7 + 7 s 6 t + 21 s 5 t 2 + 35 s 4 t 3
    + 35 s 3 t 4 + 21 s 2 t 5 + 7 s t 6 + t 7 + 35 s 3 t 4 + 21 s 2 t 5 + 7 s t 6 + t 7

    219.

    y 4 12 y 3 + 54 y 2 108 y + 81 y 4 12 y 3 + 54 y 2 108 y + 81

    221.

    q 3 12 q 2 + 48 q 64 q 3 12 q 2 + 48 q 64

    223.

    625 x 4 1000 x 3 y + 600 x 2 y 2 625 x 4 1000 x 3 y + 600 x 2 y 2
    160 x y 3 + 16 y 4 160 x y 3 + 16 y 4

    225.

    243 x 5 + 1620 x 4 y + 4320 x 3 y 2 243 x 5 + 1620 x 4 y + 4320 x 3 y 2
    + 5760 x 2 y 3 + 3840 x y 4 + 1024 y 5 + 5760 x 2 y 3 + 3840 x y 4 + 1024 y 5

    227.

    126 a 5 b 4 126 a 5 b 4

    229.

    462 x 5 y 6 462 x 5 y 6

    231.

    112

    233.

    324

    235.

    30,618

    237.

    Answers will vary.

    239.

    Answers will vary.

    Review Exercises

    241.

    7 , 13 , 31 , 85 , 247 7 , 13 , 31 , 85 , 247

    243.

    3 4 , 5 16 , 7 64 , 9 256 , 11 1024 3 4 , 5 16 , 7 64 , 9 256 , 11 1024

    245.

    a n = 9 n a n = 9 n

    247.

    a n = e n 4 a n = e n 4

    249.

    a n = n n + 2 a n = n n + 2

    251.

    1 6 , 1 12 , 1 20 , 1 30 , 1 42 1 6 , 1 12 , 1 20 , 1 30 , 1 42

    253.

    −3 + ( −1 ) + 1 + 3 + 5 −3 + ( −1 ) + 1 + 3 + 5
    + 7 + 9 = 21 + 7 + 9 = 21

    255.

    4 + 4 + 2 + 2 3 + 1 6 = 65 6 4 + 4 + 2 + 2 3 + 1 6 = 65 6

    257.

    n = 1 5 ( −1 ) n 1 3 n n = 1 5 ( −1 ) n 1 3 n

    259.

    n = 1 5 4 n n = 1 5 4 n

    261.

    The sequence is arithmetic with common difference d=6.d=6.

    263.

    5 , 8 , 11 , 14 , 17 5 , 8 , 11 , 14 , 17

    265.

    −13 , −7 , −1 , 5 , 11 −13 , −7 , −1 , 5 , 11

    267.

    −129 −129

    269.

    a18=103.a18=103. The general term is an=7n23.an=7n23.

    271.

    a1=1,a1=1,d=4.d=4. The general term is an=4n3.an=4n3.

    273.

    −1,095 −1,095

    275.

    585 585

    277.

    4,850 4,850

    279.

    980 980

    281.

    The sequence is not geometric.

    283.

    The sequence is geometric with common ratio r=−2.r=−2.

    285.

    128 , 32 , 8 , 2 , 1 2 128 , 32 , 8 , 2 , 1 2

    287.

    1,536 1,536

    289.

    a12=−25,165,824.a12=−25,165,824. The general term is an=6(−4)n1.an=6(−4)n1.

    291.

    −43,692

    293.

    3906.25 3906.25

    295.

    189 8 = 23.625 189 8 = 23.625

    297.

    343 6 57.167 343 6 57.167

    299.

    4 11 4 11

    301.

    $ 1,634,421.27 $ 1,634,421.27

    303.

    x 4 4 x 3 y + 6 x 2 y 2 4 x y 3 + y 4 x 4 4 x 3 y + 6 x 2 y 2 4 x y 3 + y 4

    305.

    32 y 5 240 y 4 + 720 y 3 1080 y 2 32 y 5 240 y 4 + 720 y 3 1080 y 2
    + 810 y 243 + 810 y 243

    307.

    11 1 1 56

    309.

    1 1 1 55

    311.

    t 9 9 t 8 + 36 t 7 84 t 6 + 126 t 5 t 9 9 t 8 + 36 t 7 84 t 6 + 126 t 5
    126 t 4 + 84 t 3 36 t 2 + 9 t 1 126 t 4 + 84 t 3 36 t 2 + 9 t 1

    313.

    256 x 4 + 768 x 3 y + 864 x 2 y 2 256 x 4 + 768 x 3 y + 864 x 2 y 2
    + 432 x y 3 + 81 y 4 + 432 x y 3 + 81 y 4

    315.

    84 a 3 b 6 84 a 3 b 6

    317.

    135

    319.

    280

    Practice Test

    321.

    1 4 , 1 5 , 1 6 , 1 7 , 1 8 1 4 , 1 5 , 1 6 , 1 7 , 1 8

    323.

    −4 + 16 64 + 256 = 204 −4 + 16 64 + 256 = 204

    325.

    −13 , −10 , −7 , −4 , −1 −13 , −10 , −7 , −4 , −1

    327.

    a23=59.a23=59. The general term is an=3n10.an=3n10.

    329.

    1,325 1,325

    331.

    3,260 3,260

    333.

    The sequence is geometric with common ratio r=13.r=13.

    335.

    5,242,880 5,242,880

    337.

    797,162 797,162

    339.

    5 6 5 6

    341.

    $ 1,409,344.19 $ 1,409,344.19

    343.

    8 1 1 210


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