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Mathematics LibreTexts

13.1.12: Chapter 12

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Be Prepared

12.1

5, 7, 9, 11

12.2

−1,1,−1,1

12.3

20

12.4

3, 7, 11, 15

12.5

(5,2)

12.6

654

12.7

34

12.8

81; 116

12.9

12; 36; 108

12.10

35

12.11

9x2+30x+25

12.12

x22xy+y2

Try It

12.1

−1,2,5,8,11

12.2

−3,−1,1,3,5

12.3

7,13,31,85,247

12.4

−3,−1,3,11,27

12.5

−1,4,−9,16,−25

12.6

1,−8,27,−64,125

12.7

an=3n

12.8

an=5n

12.9

an=(−1)n3n

12.10

an=(−1)n+1n2

12.11

an=12n

12.12

an=1n2

12.13

2,1,13,112,160

12.14

3,32,12,18,140

12.15

12,16,112,120,130

12.16

12,13,14,15,16

12.17

45

12.18

60

12.19

163

12.20

8

12.21

5n=112n

12.22

5n=11n2

12.23

5n=1(−1)n+1n2

12.24

5n=1(−1)n2n

12.25

The sequence is arithmetic with common difference d=11. The sequence is arithmetic with common difference d=−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.
The sequence is arithmetic with common difference d=−5.

12.27

7,3,−1,−5,−9,

12.28

11,3,−5,−13,−21,

12.29

241

12.30

−106

12.31

a11=2. The general term is an=−3n+35.

12.32

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

12.33

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

12.34

a1=8,d=−3. The general term is 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. The sequence is geometric with common ratio 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. The sequence is geometric with common ratio r=12.

12.43

7,−21,63,−189,567

12.44

6,−24,96,−384,1536

12.45

16,561

12.46

116,384

12.47

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

12.48

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

12.49

3,145,725

12.50

10,460,353,200

12.51

393,204

12.52

10,230

12.53

96

12.54

2563

12.55

49

12.56

89

12.57

$10,000

12.58

$3,333.33

12.59

$88,868.36

12.60

$698,201.57

12.61

x5+5x4y+10x3y2+10x2y3
+5xy4+y5

12.62

p7+7p6q+21p5q2+35p4q3
+35p3q4+21p2q5+7pq6+q7

12.63

x4+8x3+24x2+32x+16

12.64

x6+6x5+15x4+20x3+15x2
+6x+1

12.65

16x496x3+216x2216x+81

12.66

64x6192x5+240x4160x3
+60x212x+1

12.67

6 1 1 35

12.68

2 1 1 6

12.69

x5+5x4y+10x3y2+10x2y3
+5xy4+y5

12.70

m6+6m5n+15m4n2+20m3n3
+15m2n4+6mn5+n6

12.71

x515x4+90x3270x2
+405x243

12.72

y66y5+15y420y3+15y2
6y+1

12.73

243x5810x4y+1080x3y2
720x2y3+240xy432y5

12.74

256x4768x3y+864x2y2
432xy3+81y4

12.75

15x4y2

12.76

70a4b4

12.77

3,584

12.78

280

Section 12.1 Exercises

1.

−5,−3,−1,1,3

3.

4,7,10,13,16

5.

5,7,11,19,35

7.

1,5,21,73,233

9.

2,1,89,1,3225

11.

1,32,54,78,916

13.

−2,4,−6,8,−10

15.

1,−4,9,−16,25

17.

1,14,19,116,125

19.

an=8n

21.

an=n+5

23.

an=en+2

25.

an=(−1)n5n

27.

an=(−1)nn3

29.

an=(−1)n2n

31.

an=14n

33.

an=nn+1

35.

an=52n

37.

4,2,23,16,130

39.

3,6,18,72,360

41.

2,24,720,40320,3628800

43.

1,12,13,14,15

45.

1,12,23,32,245

47.

2,32,83,152,1445

49.

1+4+9+16+25=55

51.

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

53.

2+4+8+16=30

55.

41+41+42+46=323=1023

57.

2+6+12+20+30=70

59.

12+23+34+45+56=7120

61.

5n=113n

63.

5n=11n3

65.

5n=12n

67.

5n=1(−1)n+13n

69.

10n=1(−1)n2n

71.

7n=1(2n+12)

73.

Answers will vary.

75.

Answers will vary.

Section 12.2 Exercises

77.

The sequence is arithmetic with common difference d=8.

79.

The sequence is not arithmetic.

81.

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

83.

11,18,25,32,39

85.

−7,−3,1,5,9

87.

14,5,−4,−13,−22

89.

163

91.

131

93.

−79

95.

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

97.

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

99.

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

101.

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

103.

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

105.

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

107.

1,635

109.

−1,065

111.

360

113.

6,325

115.

–3,575

117.

6,280

119.

4,125

121.

−3,850

123.

Answers will vary.

125.

Answers will vary.

Section 12.3 Exercises

127.

The sequence is geometric with common ratio r=4.

129.

The sequence is geometric with common ratio r=12.

131.

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

133.

The sequence is geometric with common ratio r=12.

135.

The sequence is arithmetic with common difference d=5.

137.

The sequence is geometric with common ratio r=12.

139.

4,12,36,108,324

141.

−4,8,−16,32,−64

143.

27,9,3,1,13

145.

472,392

147.

3,072

149.

0.0001

151.

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

153.

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

155.

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

157.

57,395,624

159.

−65,538

161.

7,174,45359,049121.5

163.

65,534

165.

4088

167.

29,52465614.5

169.

32

171.

92

173.

no sum as r1

175.

2,048

177.

13

179.

79

181.

511

183.

$6666.67 $4000 $15,000 $7500

185.

$295,581.88

187.

$14,234.10

189.

Answers will vary.

191.

Answers will vary.

Section 12.4 Exercises

193.

a8+8a7b+28a6b2+56a5b3
+70a4b4+56a3b5+28a2b6
+8ab7+b8

195.

p9+9p8q+36p7q2+84p6q3
+126p5q4+126p4q5+84p3q6
+36p2q7+9pq8+q9

197.

a66a5b+15a4b220a3b3
+15a2b46ab5+b6

199.

x3+15x2+75x+125

201.

y7+7y6+21y5+35y4+35y3
+21y2+7y+1

203.

z612z5+60z4160z3+240z2
192z+64

205.

243x5405x4+270x390x2
+15x1

207.

27x3135x2+225x125

209.

27x3+135x2y+225xy2+125y3

211.

7 1 1 45

213.

4 1 1 55

215.

m5+5m4n+10m3n2+10m2n3
+5mn4+n5

217.

s7+7s6t+21s5t2+35s4t3
+35s3t4+21s2t5+7st6+t7

219.

y412y3+54y2108y+81

221.

q312q2+48q64

223.

625x41000x3y+600x2y2
160xy3+16y4

225.

243x5+1620x4y+4320x3y2
+5760x2y3+3840xy4+1024y5

227.

126a5b4

229.

462x5y6

231.

112

233.

324

235.

30,618

237.

Answers will vary.

239.

Answers will vary.

Review Exercises

241.

7,13,31,85,247

243.

34,516,764,9256,111024

245.

an=9n

247.

an=en4

249.

an=nn+2

251.

16,112,120,130,142

253.

−3+(−1)+1+3+5
+7+9=21

255.

4+4+2+23+16=656

257.

5n=1(−1)n13n

259.

5n=14n

261.

The sequence is arithmetic with common difference d=6.

263.

5,8,11,14,17

265.

−13,−7,−1,5,11

267.

−129

269.

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

271.

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

273.

−1,095

275.

585

277.

4,850

279.

980

281.

The sequence is not geometric.

283.

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

285.

128,32,8,2,12

287.

1,536

289.

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

291.

−43,692

293.

3906.25

295.

1898=23.625

297.

343657.167

299.

411

301.

$1,634,421.27

303.

x44x3y+6x2y24xy3+y4

305.

32y5240y4+720y31080y2
+810y243

307.

11 1 1 56

309.

1 1 1 55

311.

t99t8+36t784t6+126t5
126t4+84t336t2+9t1

313.

256x4+768x3y+864x2y2
+432xy3+81y4

315.

84a3b6

317.

135

319.

280

Practice Test

321.

14,15,16,17,18

323.

−4+1664+256=204

325.

−13,−10,−7,−4,−1

327.

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

329.

1,325

331.

3,260

333.

The sequence is geometric with common ratio r=13.

335.

5,242,880

337.

797,162

339.

56

341.

$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.

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