13.1.12: Chapter 12
( \newcommand{\kernel}{\mathrm{null}\,}\)
Be Prepared
5, 7, 9, 11
−1,1,−1,1
20
3, 7, 11, 15
(5,2)
654
34
ⓐ 81; ⓑ 116
ⓐ 12; ⓑ 36; ⓒ 108
35
9x2+30x+25
x2−2xy+y2
Try It
−1,2,5,8,11
−3,−1,1,3,5
7,13,31,85,247
−3,−1,3,11,27
−1,4,−9,16,−25
1,−8,27,−64,125
an=3n
an=5n
an=(−1)n3n
an=(−1)n+1n2
an=12n
an=1n2
2,1,13,112,160
3,32,12,18,140
12,16,112,120,130
12,13,14,15,16
45
60
163
8
5∑n=112n
5∑n=11n2
5∑n=1(−1)n+1n2
5∑n=1(−1)n2n
ⓐ 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.
ⓐ 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.
7,3,−1,−5,−9,…
11,3,−5,−13,−21,…
241
−106
a11=2. The general term is an=−3n+35.
a19=−55. The general term is an=−4n+21.
a1=5,d=4. The general term is an=4n+1.
a1=8,d=−3. The general term is an=−3n+11.
1,890
1,515
2,300
5,250
2,670
3,045
ⓐ 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.
ⓐ 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.
7,−21,63,−189,567
6,−24,96,−384,1536
16,561
116,384
a9=39,366. The general term is an=6(3)n−1.
a11=7,168. The general term is an=7(2)n−1.
3,145,725
10,460,353,200
393,204
10,230
96
2563
49
89
$10,000
$3,333.33
$88,868.36
$698,201.57
x5+5x4y+10x3y2+10x2y3
+5xy4+y5
p7+7p6q+21p5q2+35p4q3
+35p3q4+21p2q5+7pq6+q7
x4+8x3+24x2+32x+16
x6+6x5+15x4+20x3+15x2
+6x+1
16x4−96x3+216x2−216x+81
64x6−192x5+240x4−160x3
+60x2−12x+1
ⓐ 6 ⓑ 1 ⓒ 1 ⓓ 35
ⓐ 2 ⓑ 1 ⓒ 1 ⓓ 6
x5+5x4y+10x3y2+10x2y3
+5xy4+y5
m6+6m5n+15m4n2+20m3n3
+15m2n4+6mn5+n6
x5−15x4+90x3−270x2
+405x−243
y6−6y5+15y4−20y3+15y2
−6y+1
243x5−810x4y+1080x3y2
−720x2y3+240xy4−32y5
256x4−768x3y+864x2y2
−432xy3+81y4
15x4y2
70a4b4
3,584
280
Section 12.1 Exercises
−5,−3,−1,1,3
4,7,10,13,16
5,7,11,19,35
1,5,21,73,233
2,1,89,1,3225
1,32,54,78,916
−2,4,−6,8,−10
1,−4,9,−16,25
1,−14,19,−116,125
an=8n
an=n+5
an=en+2
an=(−1)n5n
an=(−1)nn3
an=(−1)n2n
an=14n
an=−nn+1
an=−52n
4,2,23,16,130
3,6,18,72,360
2,24,720,40320,3628800
1,12,13,14,15
1,12,23,32,245
2,32,83,152,1445
1+4+9+16+25=55
5+7+9+11+13+15=60
2+4+8+16=30
41+41+42+46=323=1023
2+6+12+20+30=70
12+23+34+45+56=7120
5∑n=113n
5∑n=11n3
5∑n=12n
5∑n=1(−1)n+13n
10∑n=1(−1)n2n
7∑n=1(2n+12)
Answers will vary.
Answers will vary.
Section 12.2 Exercises
The sequence is arithmetic with common difference d=8.
The sequence is not arithmetic.
The sequence is arithmetic with common difference d=−3.
11,18,25,32,39
−7,−3,1,5,9
14,5,−4,−13,−22
163
131
−79
a20=−34. The general term is an=−2n+6.
a11=59. The general term is an=5n+4.
a8=−13. The general term is an=−5n+27.
a1=11,d=3. The general term is an=3n+8.
a1=21,d=−8. The general term is an=−8n+29.
a1=−15,d=3. The general term is an=3n−18.
1,635
−1,065
360
6,325
–3,575
6,280
4,125
−3,850
Answers will vary.
Answers will vary.
Section 12.3 Exercises
The sequence is geometric with common ratio r=4.
The sequence is geometric with common ratio r=12.
The sequence is geometric with a common ratio r=−2.
The sequence is geometric with common ratio r=12.
The sequence is arithmetic with common difference d=5.
The sequence is geometric with common ratio r=12.
4,12,36,108,324
−4,8,−16,32,−64
27,9,3,1,13
472,392
3,072
0.0001
a9=2,304. The general term is an=9(2)n−1.
a15=−219,683. The general term is an=−486(−13)n−1.
a10=0.000000001. The general term is an=(0.1)n−1.
57,395,624
−65,538
7,174,45359,049≈121.5
65,534
4088
29,5246561≈4.5
32
92
no sum as r≥1
2,048
13
79
511
ⓐ $6666.67 ⓑ $4000 ⓒ $15,000 ⓒ $7500
$295,581.88
$14,234.10
Answers will vary.
Answers will vary.
Section 12.4 Exercises
a8+8a7b+28a6b2+56a5b3
+70a4b4+56a3b5+28a2b6
+8ab7+b8
p9+9p8q+36p7q2+84p6q3
+126p5q4+126p4q5+84p3q6
+36p2q7+9pq8+q9
a6−6a5b+15a4b2−20a3b3
+15a2b4−6ab5+b6
x3+15x2+75x+125
y7+7y6+21y5+35y4+35y3
+21y2+7y+1
z6−12z5+60z4−160z3+240z2
−192z+64
243x5−405x4+270x3−90x2
+15x−1
27x3−135x2+225x−125
27x3+135x2y+225xy2+125y3
ⓐ 7 ⓑ 1 ⓒ 1 ⓓ 45
ⓐ 4 ⓑ 1 ⓒ 1 ⓓ 55
m5+5m4n+10m3n2+10m2n3
+5mn4+n5
s7+7s6t+21s5t2+35s4t3
+35s3t4+21s2t5+7st6+t7
y4−12y3+54y2−108y+81
q3−12q2+48q−64
625x4−1000x3y+600x2y2
−160xy3+16y4
243x5+1620x4y+4320x3y2
+5760x2y3+3840xy4+1024y5
126a5b4
462x5y6
112
324
30,618
Answers will vary.
Answers will vary.
Review Exercises
7,13,31,85,247
34,516,764,9256,111024
an=9n
an=en−4
an=−nn+2
16,112,120,130,142
−3+(−1)+1+3+5
+7+9=21
4+4+2+23+16=656
5∑n=1(−1)n13n
5∑n=14n
The sequence is arithmetic with common difference d=6.
5,8,11,14,17
−13,−7,−1,5,11
−129
a18=103. The general term is an=7n−23.
a1=1,d=4. The general term is an=4n−3.
−1,095
585
4,850
980
The sequence is not geometric.
The sequence is geometric with common ratio r=−2.
128,32,8,2,12
1,536
a12=−25,165,824. The general term is an=6(−4)n−1.
−43,692
3906.25
1898=23.625
3436≈57.167
411
$1,634,421.27
x4−4x3y+6x2y2−4xy3+y4
32y5−240y4+720y3−1080y2
+810y−243
ⓐ 11 ⓑ 1 ⓒ 1 ⓓ 56
ⓐ 1 ⓑ 1 ⓒ 1 ⓓ 55
t9−9t8+36t7−84t6+126t5
−126t4+84t3−36t2+9t−1
256x4+768x3y+864x2y2
+432xy3+81y4
84a3b6
135
280
Practice Test
14,15,16,17,18
−4+16−64+256=204
−13,−10,−7,−4,−1
a23=59. The general term is an=3n−10.
1,325
3,260
The sequence is geometric with common ratio r=13.
5,242,880
797,162
56
$1,409,344.19
ⓐ 8 ⓑ 1 ⓒ 1 ⓓ 210