Skip to main content
Mathematics LibreTexts

13.1.12: Chapter 12

  • Page ID
    117747
  • \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \( \newcommand{\dsum}{\displaystyle\sum\limits} \)

    \( \newcommand{\dint}{\displaystyle\int\limits} \)

    \( \newcommand{\dlim}{\displaystyle\lim\limits} \)

    \( \newcommand{\id}{\mathrm{id}}\) \( \newcommand{\Span}{\mathrm{span}}\)

    ( \newcommand{\kernel}{\mathrm{null}\,}\) \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\) \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\) \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\id}{\mathrm{id}}\)

    \( \newcommand{\Span}{\mathrm{span}}\)

    \( \newcommand{\kernel}{\mathrm{null}\,}\)

    \( \newcommand{\range}{\mathrm{range}\,}\)

    \( \newcommand{\RealPart}{\mathrm{Re}}\)

    \( \newcommand{\ImaginaryPart}{\mathrm{Im}}\)

    \( \newcommand{\Argument}{\mathrm{Arg}}\)

    \( \newcommand{\norm}[1]{\| #1 \|}\)

    \( \newcommand{\inner}[2]{\langle #1, #2 \rangle}\)

    \( \newcommand{\Span}{\mathrm{span}}\) \( \newcommand{\AA}{\unicode[.8,0]{x212B}}\)

    \( \newcommand{\vectorA}[1]{\vec{#1}}      % arrow\)

    \( \newcommand{\vectorAt}[1]{\vec{\text{#1}}}      % arrow\)

    \( \newcommand{\vectorB}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \( \newcommand{\vectorC}[1]{\textbf{#1}} \)

    \( \newcommand{\vectorD}[1]{\overrightarrow{#1}} \)

    \( \newcommand{\vectorDt}[1]{\overrightarrow{\text{#1}}} \)

    \( \newcommand{\vectE}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash{\mathbf {#1}}}} \)

    \( \newcommand{\vecs}[1]{\overset { \scriptstyle \rightharpoonup} {\mathbf{#1}} } \)

    \(\newcommand{\longvect}{\overrightarrow}\)

    \( \newcommand{\vecd}[1]{\overset{-\!-\!\rightharpoonup}{\vphantom{a}\smash {#1}}} \)

    \(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)

    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)n−1.an=6(3)n−1.

    12.48

    a11=7,168.a11=7,168. The general term is an=7(2)n−1.an=7(2)n−1.

    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=3n−18.an=3n−18.

    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)n−1.an=9(2)n−1.

    153.

    a15=−219,683.a15=−219,683. The general term is an=−486(−13)n−1.an=−486(−13)n−1.

    155.

    a10=0.000000001.a10=0.000000001. The general term is an=(0.1)n−1.an=(0.1)n−1.

    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 r≥1r≥1

    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=7n−23.an=7n−23.

    271.

    a1=1,a1=1,d=4.d=4. The general term is an=4n−3.an=4n−3.

    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)n−1.an=6(−4)n−1.

    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=3n−10.an=3n−10.

    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


    13.1.12: Chapter 12 is shared under a not declared license and was authored, remixed, and/or curated by LibreTexts.

    • Was this article helpful?