Every problem in the chapter beside the book’s answer, a chapter at a time as you scroll.

Chapter 12: Sequences, Series and Binomial Theorem

262 problems · 0 figures

Be Prepared 12.1 §12.1 source ↗

Evaluate 2n+3 for the integers 1, 2, 3, and 4.
If you missed this problem, review Example 1.6.
Example 1.6 in the book ↗

Answer

5, 7, 9, 11

Be Prepared 12.2 §12.1 source ↗

Evaluate (−1)n for the integers 1, 2, 3, and 4.
If you missed this problem, review Example 1.19.
Example 1.19 in the book ↗

Answer

−1 , 1 , −1 , 1

Be Prepared 12.3 §12.1 source ↗

If f(n)=n2+2, find f(1)+ f(2)+ f(3).
If you missed this problem, review Example 3.49.
Example 3.49 in the book ↗

Answer

20

Try It 12.1 §12.1 source ↗

Write the first five terms of the sequence whose general term is an=3n−4.

Answer

−1 , 2 , 5 , 8 , 11

Try It 12.2 §12.1 source ↗

Write the first five terms of the sequence whose general term is an=2n−5.

Answer

−3 , −1 , 1 , 3 , 5

Try It 12.3 §12.1 source ↗

Write the first five terms of the sequence whose general term is an=3n+4.

Answer

7, 13, 31, 85, 247

Try It 12.4 §12.1 source ↗

Write the first five terms of the sequence whose general term is an=2n−5.

Answer

−3, −1, 3, 11, 27

Try It 12.5 §12.1 source ↗

Write the first five terms of the sequence whose general term is an=(−1)nn2.

Answer

−1, 4, −9, 16, −25

Try It 12.6 §12.1 source ↗

Write the first five terms of the sequence whose general term is an= (−1)n+1n3.

Answer

1, −8, 27, −64, 125

Try It 12.7 §12.1 source ↗

Find a general term for the sequence whose first five terms are shown.

3, 6, 9, 12, 15, …

Answer

a n = 3 n

Try It 12.8 §12.1 source ↗

Find a general term for the sequence whose first five terms are shown.

5, 10, 15, 20, 25, …

Answer

a n = 5 n

Try It 12.9 §12.1 source ↗

Find a general term for the sequence whose first five terms are shown.

−3, 9, −27, 81, −243,…

Answer

a n = ( −1 ) n 3 n

Try It 12.10 §12.1 source ↗

Find a general term for the sequence whose first five terms are shown

1, −4, 9, −16, 25,…

Answer

a n = ( −1 ) n + 1 n 2

Try It 12.11 §12.1 source ↗

Find a general term for the sequence whose first five terms are shown.

12, 14, 18, 116, 132, …

Answer

a n = 1 2 n

Try It 12.12 §12.1 source ↗

Find a general term for the sequence whose first five terms are shown.

11, 14, 19, 116, 125, …

Answer

a n = 1 n 2

Try It 12.13 §12.1 source ↗

Write the first five terms of the sequence whose general term is an=2n!.

Answer

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

Try It 12.14 §12.1 source ↗

Write the first five terms of the sequence whose general term is an=3n!.

Answer

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

Try It 12.15 §12.1 source ↗

Write the first five terms of the sequence whose general term is an= (n−1)!(n+1)!.

Answer

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

Try It 12.16 §12.1 source ↗

Write the first five terms of the sequence whose general term is an= n!(n+1)!.

Answer

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

Try It 12.17 §12.1 source ↗

Expand the partial sum and find its value: ∑i=153i.

Answer

45

Try It 12.18 §12.1 source ↗

Expand the partial sum and find its value: ∑i=154i.

Answer

60

Try It 12.19 §12.1 source ↗

Expand the partial sum and find its value: ∑k=032k!.

Answer

16 3

Try It 12.20 §12.1 source ↗

Expand the partial sum and find its value: ∑k=033k!.

Answer

8

Try It 12.21 §12.1 source ↗

Write the sum using summation notation: 12+ 14+ 18+ 116+ 132.

Answer

∑ n = 1 5 1 2 n

Try It 12.22 §12.1 source ↗

Write the sum using summation notation: 1+ 14+ 19+ 116+ 125.

Answer

∑ n = 1 5 1 n 2

Try It 12.23 §12.1 source ↗

Write each sum using summation notation: 1− 4+ 9− 16+ 25.

Answer

∑ n = 1 5 ( −1 ) n + 1 n 2

Try It 12.24 §12.1 source ↗

Write each sum using summation notation: −2+ 4− 6+ 8− 10.

Answer

∑ n = 1 5 ( −1 ) n 2 n

12.1-1 §12.1 source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = 2 n − 7

Answer

−5, −3, −1, 1, 3

12.1-3 §12.1 source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = 3 n + 1

Answer

4, 7, 10, 13, 16

12.1-5 §12.1 source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = 2 n + 3

Answer

5, 7, 11, 19, 35

12.1-7 §12.1 source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = 3 n − 2 n

Answer

1, 5, 21, 73, 233

12.1-9 §12.1 source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = 2 n n 2

Answer

2, 1, 8 9 , 1, 32 25

12.1-11 §12.1 source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = 4 n − 2 2 n

Answer

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

12.1-13 §12.1 source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = ( −1 ) n · 2 n

Answer

−2, 4, −6, 8, −10

12.1-15 §12.1 source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = ( −1 ) n + 1 n 2

Answer

1, −4, 9, −16, 25

12.1-17 §12.1 source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = ( −1 ) n + 1 n 2

Answer

1, − 1 4 , 1 9 , − 1 16 , 1 25

12.1-19 §12.1 source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

8, 16, 24, 32, 40, …

Answer

a n = 8 n

12.1-21 §12.1 source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

6, 7, 8, 9, 10, …

Answer

a n = n + 5

12.1-23 §12.1 source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

e 3 , e 4 , e 5 , e 6 , e 7 , …

Answer

a n = e n + 2

12.1-25 §12.1 source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

−5, 10, −15, 20, −25, …

Answer

a n = ( −1 ) n 5 n

12.1-27 §12.1 source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

−1, 8, −27, 64, −125, …

Answer

a n = ( −1 ) n n 3

12.1-29 §12.1 source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

−2, 4, −6, 8, −10, …

Answer

a n = ( −1 ) n 2 n

12.1-31 §12.1 source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

1 4 , 1 16 , 1 64 , 1 256 , 1 1,024 , …

Answer

a n = 1 4 n

12.1-33 §12.1 source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

− 1 2 , − 2 3 , − 3 4 , − 4 5 , − 5 6 , …

Answer

a n = − n n + 1

12.1-35 §12.1 source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

− 5 2 , − 5 4 , − 5 8 , − 5 16 , − 5 32 , …

Answer

a n = − 5 2 n

12.1-37 §12.1 source ↗

Use Factorial Notation

In the following exercises, using factorial notation, write the first five terms of the sequence whose general term is given.

a n = 4 n !

Answer

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

12.1-39 §12.1 source ↗

Use Factorial Notation

In the following exercises, using factorial notation, write the first five terms of the sequence whose general term is given.

a n = 3 n !

Answer

3, 6, 18, 72, 360

12.1-41 §12.1 source ↗

Use Factorial Notation

In the following exercises, using factorial notation, write the first five terms of the sequence whose general term is given.

a n = ( 2 n ) !

Answer

2, 24, 720, 40320, 3628800

12.1-43 §12.1 source ↗

Use Factorial Notation

In the following exercises, using factorial notation, write the first five terms of the sequence whose general term is given.

a n = ( n − 1 ) ! ( n ) !

Answer

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

12.1-45 §12.1 source ↗

Use Factorial Notation

In the following exercises, using factorial notation, write the first five terms of the sequence whose general term is given.

a n = n ! n 2

Answer

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

12.1-47 §12.1 source ↗

Use Factorial Notation

In the following exercises, using factorial notation, write the first five terms of the sequence whose general term is given.

a n = ( n + 1 ) ! n 2

Answer

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

12.1-49 §12.1 source ↗

Find the Partial Sum

In the following exercises, expand the partial sum and find its value.

∑ i = 1 5 i 2

Answer

1+ 4+ 9+ 16+ 25= 55

12.1-51 §12.1 source ↗

Find the Partial Sum

In the following exercises, expand the partial sum and find its value.

∑ i = 1 6 ( 2 i + 3 )

Answer

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

12.1-53 §12.1 source ↗

Find the Partial Sum

In the following exercises, expand the partial sum and find its value.

∑ i = 1 4 2 i

Answer

2 + 4 + 8 + 16 = 30

12.1-55 §12.1 source ↗

Find the Partial Sum

In the following exercises, expand the partial sum and find its value.

∑ k = 0 3 4 k !

Answer

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

12.1-57 §12.1 source ↗

Find the Partial Sum

In the following exercises, expand the partial sum and find its value.

∑ k = 1 5 k ( k + 1 )

Answer

2+ 6+ 12+ 20+ 30= 70

12.1-59 §12.1 source ↗

Find the Partial Sum

In the following exercises, expand the partial sum and find its value.

∑ n = 1 5 n n + 1

Answer

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

12.1-61 §12.1 source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

1 3 + 1 9 + 1 27 + 1 81 + 1 243

Answer

∑ n = 1 5 1 3 n

12.1-63 §12.1 source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

1+ 1 8 + 1 27 + 1 64 + 1 125

Answer

∑ n = 1 5 1 n 3

12.1-65 §12.1 source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

2+ 1+ 2 3 + 1 2 + 2 5

Answer

∑ n = 1 5 2 n

12.1-67 §12.1 source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

3 − 6 + 9 − 12 + 15

Answer

∑ n = 1 5 ( −1 ) n + 1 3 n

12.1-69 §12.1 source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

−2+ 4− 6+ 8− 10+ …+ 20

Answer

∑ n = 1 10 ( −1 ) n 2 n

12.1-71 §12.1 source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

14+ 16+ 18+ 20+ 22+ 24+ 26

Answer

∑ n = 1 7 ( 2 n + 12 )

12.1-73 §12.1 source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

In your own words, explain how to write the terms of a sequence when you know the formula. Show an example to illustrate your explanation.

Answer

Answers will vary.

12.1-75 §12.1 source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

In your own words, explain what is meant by n! Show some examples to illustrate your explanation.

Answer

Answers will vary.

Be Prepared 12.4 §12.2 source ↗

Evaluate 4n−1 for the integers 1, 2, 3, and 4.
If you missed this problem, review Example 1.6.
Example 1.6 in the book ↗

Answer

3, 7, 11, 15

Be Prepared 12.5 §12.2 source ↗

Solve the system of equations: {x+y=73x+4y=23.
If you missed this problem, review Example 4.9.
Example 4.9 in the book ↗

Answer

( 5 , 2 )

Be Prepared 12.6 §12.2 source ↗

If f(n)= n2(3n+5), find f(1)+f(20).
If you missed this problem, review Example 3.49.
Example 3.49 in the book ↗

Answer

654

Try It 12.25 §12.2 source ↗

Determine if each sequence is arithmetic. If so, indicate the common difference.

ⓐ 9, 20, 31, 42, 53, 64,… ⓑ 12, 6, 0, −6, −12, −18,… ⓒ 7, 1, 10, 4, 13, 7,…

Answer

ⓐ 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.

Try It 12.26 §12.2 source ↗

Determine if each sequence is arithmetic. If so, indicate the common difference.

ⓐ −4, 4, 2, 10, 8, 16,… ⓑ −3, −1, 1, 3, 5, 7,… ⓒ 7, 2, −3, −8, −13, −18,…

Answer

ⓐ 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.

Try It 12.27 §12.2 source ↗

Write the first five terms of the sequence where the first term is 7 and the common difference is d=−4.

Answer

7, 3, −1, −5, −9,…

Try It 12.28 §12.2 source ↗

Write the first five terms of the sequence where the first term is 11 and the common difference is d=−8.

Answer

11, 3, −5, −13, −21,…

Try It 12.29 §12.2 source ↗

Find the twenty-seventh term of a sequence where the first term is 7 and the common difference is 9.

Answer

241

Try It 12.30 §12.2 source ↗

Find the eighteenth term of a sequence where the first term is 13 and the common difference is −7.

Answer

−106

Try It 12.31 §12.2 source ↗

Find the eleventh term of a sequence where the ninth term is 8 and the common difference is −3. Give the formula for the general term.

Answer

a11=2. The general term is an=−3n+35.

Try It 12.32 §12.2 source ↗

Find the nineteenth term of a sequence where the fifth term is 1 and the common difference is −4. Give the formula for the general term.

Answer

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

Try It 12.33 §12.2 source ↗

Find the first term and common difference of a sequence where the fourth term is 17 and the thirteenth term is 53. Give the formula for the general term.

Answer

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

Try It 12.34 §12.2 source ↗

Find the first term and common difference of a sequence where the third term is 2 and the twelfth term is −25. Give the formula for the general term.

Answer

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

Try It 12.35 §12.2 source ↗

Find the sum of the first 30 terms of the arithmetic sequence: 5, 9, 13, 17, 21, …

Answer

1,890

Try It 12.36 §12.2 source ↗

Find the sum of the first 30 terms of the arithmetic sequence: 7, 10, 13, 16, 19, …

Answer

1,515

Try It 12.37 §12.2 source ↗

Find the sum of the first 50 terms of the arithmetic sequence whose general term is an=2n−5.

Answer

2,300

Try It 12.38 §12.2 source ↗

Find the sum of the first 50 terms of the arithmetic sequence whose general term is an=4n+3.

Answer

5,250

Try It 12.39 §12.2 source ↗

Find the sum: ∑i=130(6i−4).

Answer

2,670

Try It 12.40 §12.2 source ↗

Find the sum: ∑i=135(5i−3).

Answer

3,045

12.2-77 §12.2 source ↗

Determine if a Sequence is Arithmetic

In the following exercises, determine if each sequence is arithmetic, and if so, indicate the common difference.

4, 12, 20, 28, 36, 44,…

Answer

The sequence is arithmetic with common difference d=8.

12.2-79 §12.2 source ↗

Determine if a Sequence is Arithmetic

In the following exercises, determine if each sequence is arithmetic, and if so, indicate the common difference.

−15, −16, 3, 12, 21, 30,…

Answer

The sequence is not arithmetic.

12.2-81 §12.2 source ↗

Determine if a Sequence is Arithmetic

In the following exercises, determine if each sequence is arithmetic, and if so, indicate the common difference.

8, 5, 2, −1, −4, −7,…

Answer

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

12.2-83 §12.2 source ↗

In the following exercises, write the first five terms of each sequence with the given first term and common difference.

a1=11 and d=7

Answer

11, 18, 25, 32, 39

12.2-85 §12.2 source ↗

In the following exercises, write the first five terms of each sequence with the given first term and common difference.

a1=−7 and d=4

Answer

−7 , −3 , 1 , 5 , 9

12.2-87 §12.2 source ↗

In the following exercises, write the first five terms of each sequence with the given first term and common difference.

a1=14 and d=−9

Answer

14, 5, −4, −13, −22

12.2-89 §12.2 source ↗

Find the General Term (nth Term) of an Arithmetic Sequence

In the following exercises, find the term described using the information provided.

Find the twenty-first term of a sequence where the first term is three and the common difference is eight.

Answer

163

12.2-91 §12.2 source ↗

Find the General Term (nth Term) of an Arithmetic Sequence

In the following exercises, find the term described using the information provided.

Find the thirtieth term of a sequence where the first term is −14 and the common difference is five.

Answer

131

12.2-93 §12.2 source ↗

Find the General Term (nth Term) of an Arithmetic Sequence

In the following exercises, find the term described using the information provided.

Find the sixteenth term of a sequence where the first term is 11 and the common difference is −6.

Answer

−79

12.2-95 §12.2 source ↗

Find the General Term (nth Term) of an Arithmetic Sequence

In the following exercises, find the term described using the information provided.

Find the twentieth term of a sequence where the fifth term is −4 and the common difference is −2. Give the formula for the general term.

Answer

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

12.2-97 §12.2 source ↗

Find the General Term (nth Term) of an Arithmetic Sequence

In the following exercises, find the term described using the information provided.

Find the eleventh term of a sequence where the third term is 19 and the common difference is five. Give the formula for the general term.

Answer

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

12.2-99 §12.2 source ↗

Find the General Term (nth Term) of an Arithmetic Sequence

In the following exercises, find the term described using the information provided.

Find the eighth term of a sequence where the seventh term is −8 and the common difference is −5. Give the formula for the general term.

Answer

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

12.2-101 §12.2 source ↗

In the following exercises, find the first term and common difference of the sequence with the given terms. Give the formula for the general term.

The second term is 14 and the thirteenth term is 47.

Answer

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

12.2-103 §12.2 source ↗

In the following exercises, find the first term and common difference of the sequence with the given terms. Give the formula for the general term.

The second term is 13 and the tenth term is −51.

Answer

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

12.2-105 §12.2 source ↗

In the following exercises, find the first term and common difference of the sequence with the given terms. Give the formula for the general term.

The fourth term is −6 and the fifteenth term is 27.

Answer

a1=−15,d=3. The general term is an=3n−18.

12.2-107 §12.2 source ↗

Find the Sum of the First n Terms of an Arithmetic Sequence

In the following exercises, find the sum of the first 30 terms of each arithmetic sequence.

11, 14, 17, 20, 23,…

Answer

1,635

12.2-109 §12.2 source ↗

Find the Sum of the First n Terms of an Arithmetic Sequence

In the following exercises, find the sum of the first 30 terms of each arithmetic sequence.

8, 5, 2, −1, −4,…

Answer

−1 , 065

12.2-111 §12.2 source ↗

Find the Sum of the First n Terms of an Arithmetic Sequence

In the following exercises, find the sum of the first 30 terms of each arithmetic sequence.

−17, −15, −13, −11, −9,…

Answer

360

12.2-113 §12.2 source ↗

In the following exercises, find the sum of the first 50 terms of the arithmetic sequence whose general term is given.

a n = 5 n − 1

Answer

6,325

12.2-115 §12.2 source ↗

In the following exercises, find the sum of the first 50 terms of the arithmetic sequence whose general term is given.

a n = −3 n + 5

Answer

–3,575

12.2-117 §12.2 source ↗

In the following exercises, find each sum.

∑ i = 1 40 ( 8 i − 7 )

Answer

6,280

12.2-119 §12.2 source ↗

In the following exercises, find each sum.

∑ i = 1 50 ( 3 i + 6 )

Answer

4,125

12.2-121 §12.2 source ↗

In the following exercises, find each sum.

∑ i = 1 35 ( −6 i − 2 )

Answer

−3,850

12.2-123 §12.2 source ↗

In the following exercises, find each sum.

In your own words, explain how to determine whether a sequence is arithmetic.

Answer

Answers will vary.

12.2-125 §12.2 source ↗

In the following exercises, find each sum.

In your own words, explain how to find the general term of an arithmetic sequence.

Answer

Answers will vary.

Be Prepared 12.7 §12.3 source ↗

Simplify: 2432.
If you missed this problem, review Example 1.24.
Example 1.24 in the book ↗

Answer

3 4

Be Prepared 12.8 §12.3 source ↗

Evaluate: ⓐ 34 ⓑ (12)4.
If you missed this problem, review Example 1.19.
Example 1.19 in the book ↗

Answer

ⓐ 81; ⓑ 116

Be Prepared 12.9 §12.3 source ↗

If f(x)=4·3x, find ⓐ f(1) ⓑ f(2) ⓒ f(3).
If you missed this problem, review Example 3.49.
Example 3.49 in the book ↗

Answer

ⓐ 12; ⓑ 36; ⓒ 108

Try It 12.41 §12.3 source ↗

Determine if each sequence is geometric. If so indicate the common ratio.

ⓐ 7, 21, 63, 189, 567, 1,701,…

ⓑ 64, 16, 4, 1, 14, 116,…

ⓒ 2, 4, 12, 48, 240, 1,440,…

Answer

ⓐ 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.

Try It 12.42 §12.3 source ↗

Determine if each sequence is geometric. If so indicate the common ratio.

ⓐ −150, −30, −15, −5, − 52, 0,…

ⓑ 5, 10, 20, 40, 80, 160,…

ⓒ 8, 4, 2, 1, 12, 14,…

Answer

ⓐ 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.

Try It 12.43 §12.3 source ↗

Write the first five terms of the sequence where the first term is 7 and the common ratio is r=−3.

Answer

7, −21, 63, −189, 567

Try It 12.44 §12.3 source ↗

Write the first five terms of the sequence where the first term is 6 and the common ratio is r=−4.

Answer

6, −24, 96, −384, 1536

Try It 12.45 §12.3 source ↗

Find the thirteenth term of a sequence where the first term is 81 and the common ratio is r=13.

Answer

1 6,561

Try It 12.46 §12.3 source ↗

Find the twelfth term of a sequence where the first term is 256 and the common ratio is r=14.

Answer

1 16,384

Try It 12.47 §12.3 source ↗

Find the ninth term of the sequence 6, 18, 54, 162, 486, 1,458, … Then find the general term for the sequence.

Answer

a9=39,366. The general term is an=6(3)n−1.

Try It 12.48 §12.3 source ↗

Find the eleventh term of the sequence 7, 14, 28, 56, 112, 224, … Then find the general term for the sequence.

Answer

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

Try It 12.49 §12.3 source ↗

Find the sum of the first 20 terms of the geometric sequence 3, 6, 12, 24, 48, 96, …

Answer

3,145,725

Try It 12.50 §12.3 source ↗

Find the sum of the first 20 terms of the geometric sequence 6, 18, 54, 162, 486, 1,458, …

Answer

10,460,353,200

Try It 12.51 §12.3 source ↗

Find the sum: ∑i=1156(2)i.

Answer

393,204

Try It 12.52 §12.3 source ↗

Find the sum: ∑i=1105(2)i.

Answer

10,230

Try It 12.53 §12.3 source ↗

Find the sum of the infinite geometric series 48+ 24+ 12+ 6+ 3+ 32+ …

Answer

96

Try It 12.54 §12.3 source ↗

Find the sum of the infinite geometric series 64+ 16+ 4+ 1+ 14+ 116+ …

Answer

256 3

Try It 12.55 §12.3 source ↗

Write the repeating decimal 0.4– as a fraction.

Answer

4 9

Try It 12.56 §12.3 source ↗

Write the repeating decimal 0.8– as a fraction.

Answer

8 9

Try It 12.57 §12.3 source ↗

What is the total effect on the economy of a government tax rebate of $1,000 to each household in order to stimulate the economy if each household will spend 90% of the rebate in goods and services?

Answer

$ 10,000

Try It 12.58 §12.3 source ↗

What is the total effect on the economy of a government tax rebate of $500 to each household in order to stimulate the economy if each household will spend 85% of the rebate in goods and services?

Answer

$ 3 , 333.33

Try It 12.59 §12.3 source ↗

New grandparents decide to invest $200 per month in an annuity for their grandson. The account will pay 5% interest per year which is compounded monthly. How much will be in the child’s account at his twenty-first birthday?

Answer

$ 88,868.36

Try It 12.60 §12.3 source ↗

Arturo just got his first full-time job after graduating from college at age 27. He decided to invest $200 per month in an IRA (an annuity). The interest on the annuity is 8%, which is compounded monthly. How much will be in the Arturo’s account when he retires at his sixty-seventh birthday?

Answer

$ 698,201.57

12.3-127 §12.3 source ↗

Determine if a Sequence is Geometric

In the following exercises, determine if the sequence is geometric, and if so, indicate the common ratio.

3, 12, 48, 192, 768, 3072,…

Answer

The sequence is geometric with common ratio r=4.

12.3-129 §12.3 source ↗

Determine if a Sequence is Geometric

In the following exercises, determine if the sequence is geometric, and if so, indicate the common ratio.

72, 36, 18, 9, 9 2 , 9 4 ,…

Answer

The sequence is geometric with common ratio r=12.

12.3-131 §12.3 source ↗

Determine if a Sequence is Geometric

In the following exercises, determine if the sequence is geometric, and if so, indicate the common ratio.

−3, 6, −12, 24, −48, 96,…

Answer

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

12.3-133 §12.3 source ↗

In the following exercises, determine if each sequence is arithmetic, geometric or neither. If arithmetic, indicate the common difference. If geometric, indicate the common ratio.

48, 24, 12, 6, 3, 3 2 ,…

Answer

The sequence is geometric with common ratio r=12.

12.3-135 §12.3 source ↗

In the following exercises, determine if each sequence is arithmetic, geometric or neither. If arithmetic, indicate the common difference. If geometric, indicate the common ratio.

−7, −2, 3, 8, 13, 18,…

Answer

The sequence is arithmetic with common difference d=5.

12.3-137 §12.3 source ↗

In the following exercises, determine if each sequence is arithmetic, geometric or neither. If arithmetic, indicate the common difference. If geometric, indicate the common ratio.

1 2 , 1 4 , 1 8 , 1 16 , 1 32 , 1 64 ,…

Answer

The sequence is geometric with common ratio r=12.

12.3-139 §12.3 source ↗

In the following exercises, write the first five terms of each geometric sequence with the given first term and common ratio.

a1=4 and r=3

Answer

4, 12, 36, 108, 324

12.3-141 §12.3 source ↗

In the following exercises, write the first five terms of each geometric sequence with the given first term and common ratio.

a1=−4 and r=−2

Answer

−4, 8, −16, 32, −64

12.3-143 §12.3 source ↗

In the following exercises, write the first five terms of each geometric sequence with the given first term and common ratio.

a1=27 and r=13

Answer

27 , 9 , 3 , 1 , 1 3

12.3-145 §12.3 source ↗

Find the General Term (nth Term) of a Geometric Sequence

In the following exercises, find the indicated term of a sequence where the first term and the common ratio is given.

Find a11 given a1=8 and r=3.

Answer

472,392

12.3-147 §12.3 source ↗

Find the General Term (nth Term) of a Geometric Sequence

In the following exercises, find the indicated term of a sequence where the first term and the common ratio is given.

Find a10 given a1=−6 and r=−2.

Answer

3,072

12.3-149 §12.3 source ↗

Find the General Term (nth Term) of a Geometric Sequence

In the following exercises, find the indicated term of a sequence where the first term and the common ratio is given.

Find a10 given a1=100,000 and r=0.1.

Answer

0.0001

12.3-151 §12.3 source ↗

In the following exercises, find the indicated term of the given sequence. Find the general term for the sequence.

Find a9 of the sequence, 9, 18, 36, 72, 144, 288,…

Answer

a9=2,304. The general term is an=9(2)n−1.

12.3-153 §12.3 source ↗

In the following exercises, find the indicated term of the given sequence. Find the general term for the sequence.

Find a15 of the sequence, −486, 162, −54, 18, −6, 2,…

Answer

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

12.3-155 §12.3 source ↗

In the following exercises, find the indicated term of the given sequence. Find the general term for the sequence.

Find a10 of the sequence, 1, 0.1, 0.01, 0.001, 0.0001, 0.00001,…

Answer

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

12.3-157 §12.3 source ↗

Find the Sum of the First n terms of a Geometric Sequence

In the following exercises, find the sum of the first fifteen terms of each geometric sequence.

8, 24, 72, 216, 648, 1944,…

Answer

57,395,624

12.3-159 §12.3 source ↗

Find the Sum of the First n terms of a Geometric Sequence

In the following exercises, find the sum of the first fifteen terms of each geometric sequence.

−6, 12, −24, 48, −96, 192,…

Answer

−65,538

12.3-161 §12.3 source ↗

Find the Sum of the First n terms of a Geometric Sequence

In the following exercises, find the sum of the first fifteen terms of each geometric sequence.

81, 27, 9, 3, 1, 1 3 ,…

Answer

7,174,453 59,049 ≈ 121.5

12.3-163 §12.3 source ↗

In the following exercises, find the sum of the geometric sequence.

∑ i = 1 15 ( 2 ) i

Answer

65,534

12.3-165 §12.3 source ↗

In the following exercises, find the sum of the geometric sequence.

∑ i = 1 9 4 ( 2 ) i

Answer

4088

12.3-167 §12.3 source ↗

In the following exercises, find the sum of the geometric sequence.

∑ i = 1 10 9 ( 1 3 ) i

Answer

29,524 6561 ≈ 4.5

12.3-169 §12.3 source ↗

Find the Sum of an Infinite Geometric Series

In the following exercises, find the sum of each infinite geometric series.

1+ 1 3 + 1 9 + 1 27 + 1 81 + 1 243 + 1 729 + …

Answer

3 2

12.3-171 §12.3 source ↗

Find the Sum of an Infinite Geometric Series

In the following exercises, find the sum of each infinite geometric series.

6− 2+ 2 3 − 2 9 + 2 27 − 2 81 + …

Answer

9 2

12.3-173 §12.3 source ↗

Find the Sum of an Infinite Geometric Series

In the following exercises, find the sum of each infinite geometric series.

6+ 12+ 24+ 48+ 96+ 192+ …

Answer

no sum as r≥1

12.3-175 §12.3 source ↗

Find the Sum of an Infinite Geometric Series

In the following exercises, find the sum of each infinite geometric series.

1,024+ 512+ 256+ 128+ 64+ 32+ …

Answer

2,048

12.3-177 §12.3 source ↗

In the following exercises, write each repeating decimal as a fraction.

0. 3 –

Answer

1 3

12.3-179 §12.3 source ↗

In the following exercises, write each repeating decimal as a fraction.

0. 7 –

Answer

7 9

12.3-181 §12.3 source ↗

In the following exercises, write each repeating decimal as a fraction.

0. 45 —

Answer

5 11

12.3-183 §12.3 source ↗

Apply Geometric Sequences and Series in the Real World

In the following exercises, solve the problem.

Find the total effect on the economy of each government tax rebate to each household in order to stimulate the economy if each household will spend the indicated percent of the rebate in goods and services.

Tax rebate to each household Percent spent on goods and services Total Effect on the economy
ⓐ $1,000 85%
ⓑ $1,000 75%
ⓒ $1,500 90%
ⓓ $1,500 80%

Answer

ⓐ $6666.67 ⓑ $4000 ⓒ $15,000 ⓒ $7500

12.3-185 §12.3 source ↗

Apply Geometric Sequences and Series in the Real World

In the following exercises, solve the problem.

Berenice just got her first full-time job after graduating from college at age 30. She decided to invest $500 per quarter in an IRA (an annuity). The interest on the annuity is 7% which is compounded quarterly (4 times a year). How much will be in the Berenice’s account when she retires at age 65?

Answer

$ 295,581.88

12.3-187 §12.3 source ↗

Apply Geometric Sequences and Series in the Real World

In the following exercises, solve the problem.

Myra just got her first full-time job after graduating from college. She plans to get a master’s degree, and so is depositing $2,500 a year from her year-end bonus into an annuity. The annuity pays 6.5% per year and is compounded yearly. How much will she have saved in five years to pursue her master’s degree?

Answer

$ 14,234.10

12.3-189 §12.3 source ↗

Apply Geometric Sequences and Series in the Real World

In the following exercises, solve the problem.

In your own words, explain how to find the general term of a geometric sequence.

Answer

Answers will vary.

12.3-191 §12.3 source ↗

Apply Geometric Sequences and Series in the Real World

In the following exercises, solve the problem.

In your own words, explain how to determine if an infinite geometric series has a sum and how to find it.

Answer

Answers will vary.

Be Prepared 12.10 §12.4 source ↗

Simplify: 7·6·5·44·3·2·1.
If you missed this problem, review Example 1.25.
Example 1.25 in the book ↗

Answer

35

Be Prepared 12.11 §12.4 source ↗

Expand: (3x+5)2.
If you missed this problem, review Example 5.32.
Example 5.32 in the book ↗

Answer

9 x 2 + 30 x + 25

Be Prepared 12.12 §12.4 source ↗

Expand: (x−y)2.
If you missed this problem, review Example 5.32.
Example 5.32 in the book ↗

Answer

x 2 − 2 x y + y 2

Try It 12.61 §12.4 source ↗

Use Pascal’s Triangle to expand (x+y)5.

Answer

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

Try It 12.62 §12.4 source ↗

Use Pascal’s Triangle to expand (p+q)7.

Answer

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 + 7p q 6 + q 7

Try It 12.63 §12.4 source ↗

Use Pascal’s Triangle to expand (x+2)4.

Answer

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

Try It 12.64 §12.4 source ↗

Use Pascal’s Triangle to expand (x+1)6.

Answer

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

Try It 12.65 §12.4 source ↗

Use Pascal’s Triangle to expand (2x−3)4.

Answer

16 x 4 − 96 x 3 + 216 x 2 − 216x+ 81

Try It 12.66 §12.4 source ↗

Use Pascal’s Triangle to expand (2x−1)6.

Answer

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

Try It 12.67 §12.4 source ↗

Evaluate each binomial coefficient:

ⓐ (61) ⓑ (88) ⓒ (50) ⓓ (73).

Answer

ⓐ 6 ⓑ 1 ⓒ 1 ⓓ 35

Try It 12.68 §12.4 source ↗

Evaluate each binomial coefficient:

ⓐ (21) ⓑ (1111) ⓒ (90) ⓓ (65).

Answer

ⓐ 2 ⓑ 1 ⓒ 1 ⓓ 6

Try It 12.69 §12.4 source ↗

Use the Binomial Theorem to expand (x+y)5.

Answer

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

Try It 12.70 §12.4 source ↗

Use the Binomial Theorem to expand (m+n)6.

Answer

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

Try It 12.71 §12.4 source ↗

Use the Binomial Theorem to expand (x−3)5.

Answer

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

Try It 12.72 §12.4 source ↗

Use the Binomial Theorem to expand (y−1)6.

Answer

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

Try It 12.73 §12.4 source ↗

Use the Binomial Theorem to expand (3x−2y)5.

Answer

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

Try It 12.74 §12.4 source ↗

Use the Binomial Theorem to expand (4x−3y)4.

Answer

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

Try It 12.75 §12.4 source ↗

Find the third term of (x+y)6.

Answer

15 x 4 y 2

Try It 12.76 §12.4 source ↗

Find the fifth term of (a+b)8.

Answer

70 a 4 b 4

Try It 12.77 §12.4 source ↗

Find the coefficient of the x5 term of (x+4)8.

Answer

3,584

Try It 12.78 §12.4 source ↗

Find the coefficient of the x4 term of (x+2)7.

Answer

280

12.4-193 §12.4 source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( a + b ) 8

Answer

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
+ 8 a b 7 + b 8

12.4-195 §12.4 source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( p + q ) 9

Answer

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
+ 36 p 2 q 7 + 9p q 8 + q 9

12.4-197 §12.4 source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( a − b ) 6

Answer

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

12.4-199 §12.4 source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( x + 5 ) 3

Answer

x 3 + 15 x 2 + 75x+ 125

12.4-201 §12.4 source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( y + 1 ) 7

Answer

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

12.4-203 §12.4 source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( z − 2 ) 6

Answer

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

12.4-205 §12.4 source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( 3 x − 1 ) 5

Answer

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

12.4-207 §12.4 source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( 3 x − 5 ) 3

Answer

27 x 3 − 135 x 2 + 225x− 125

12.4-209 §12.4 source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( 3 x + 5 y ) 3

Answer

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

12.4-211 §12.4 source ↗

Evaluate a Binomial Coefficient

In the following exercises, evaluate.

ⓐ (71) ⓑ (44) ⓒ (30) ⓓ (108)

Answer

ⓐ 7 ⓑ 1 ⓒ 1 ⓓ 45

12.4-213 §12.4 source ↗

Evaluate a Binomial Coefficient

In the following exercises, evaluate.

ⓐ (41) ⓑ (55) ⓒ (80) ⓓ (119)

Answer

ⓐ 4 ⓑ 1 ⓒ 1 ⓓ 55

12.4-215 §12.4 source ↗

Use the Binomial Theorem to Expand a Binomial

In the following exercises, expand each binomial.

( m + n ) 5

Answer

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

12.4-217 §12.4 source ↗

Use the Binomial Theorem to Expand a Binomial

In the following exercises, expand each binomial.

( s + t ) 7

Answer

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 + 7s t 6 + t 7

12.4-219 §12.4 source ↗

Use the Binomial Theorem to Expand a Binomial

In the following exercises, expand each binomial.

( y − 3 ) 4

Answer

y 4 − 12 y 3 + 54 y 2 − 108y+ 81

12.4-221 §12.4 source ↗

Use the Binomial Theorem to Expand a Binomial

In the following exercises, expand each binomial.

( q − 4 ) 3

Answer

q 3 − 12 q 2 + 48q− 64

12.4-223 §12.4 source ↗

Use the Binomial Theorem to Expand a Binomial

In the following exercises, expand each binomial.

( 5 x − 2 y ) 4

Answer

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

12.4-225 §12.4 source ↗

Use the Binomial Theorem to Expand a Binomial

In the following exercises, expand each binomial.

( 3 x + 4 y ) 5

Answer

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

12.4-227 §12.4 source ↗

In the following exercises, find the indicated term in the expansion of the binomial.

Fifth term of (a+b)9

Answer

126 a 5 b 4

12.4-229 §12.4 source ↗

In the following exercises, find the indicated term in the expansion of the binomial.

Seventh term of (x−y)11

Answer

462 x 5 y 6

12.4-231 §12.4 source ↗

In the following exercises, find the coefficient of the indicated term in the expansion of the binomial.

x6 term of (x+2)8

Answer

112

12.4-233 §12.4 source ↗

In the following exercises, find the coefficient of the indicated term in the expansion of the binomial.

x7 term of (x−3)9

Answer

324

12.4-235 §12.4 source ↗

In the following exercises, find the coefficient of the indicated term in the expansion of the binomial.

p5q4 term of (3p+q)9

Answer

30,618

12.4-237 §12.4 source ↗

In the following exercises, find the coefficient of the indicated term in the expansion of the binomial.

In your own words, explain the pattern of exponents for each variable in the expansion of.

Answer

Answers will vary.

12.4-239 §12.4 source ↗

In the following exercises, find the coefficient of the indicated term in the expansion of the binomial.

In your own words, explain how to find a specific term in the expansion of a binomial without expanding the whole thing. Use an example to help explain.

Answer

Answers will vary.

12.R-241 §12.R source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = 3 n + 4

Answer

7, 13, 31, 85, 247

12.R-243 §12.R source ↗

Write the First Few Terms of a Sequence

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = 2 n + 1 4 n

Answer

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

12.R-245 §12.R source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

9, 18, 27, 36, 45, …

Answer

a n = 9 n

12.R-247 §12.R source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

1 e 3 , 1 e 2 , 1 e , 1, e, …

Answer

a n = e n − 4

12.R-249 §12.R source ↗

Find a Formula for the General Term (nth Term) of a Sequence

In the following exercises, find a general term for the sequence whose first five terms are shown.

− 1 3 , − 1 2 , − 3 5 , − 2 3 , − 5 7 , …

Answer

a n = − n n + 2

12.R-251 §12.R source ↗

Use Factorial Notation

In the following exercises, using factorial notation, write the first five terms of the sequence whose general term is given.

a n = n ! ( n + 2 ) !

Answer

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

12.R-253 §12.R source ↗

Find the Partial Sum

In the following exercises, expand the partial sum and find its value.

∑ i = 1 7 ( 2 i − 5 )

Answer

−3+ (−1)+ 1+ 3+ 5
+ 7 + 9 = 21

12.R-255 §12.R source ↗

Find the Partial Sum

In the following exercises, expand the partial sum and find its value.

∑ k = 0 4 4 k !

Answer

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

12.R-257 §12.R source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

− 1 3 + 1 9 − 1 27 + 1 81 − 1 243

Answer

∑ n = 1 5 ( −1 ) n 1 3 n

12.R-259 §12.R source ↗

Use Summation Notation to write a Sum

In the following exercises, write each sum using summation notation.

4 + 2 + 4 3 + 1 + 4 5

Answer

∑ n = 1 5 4 n

12.R-261 §12.R source ↗

Determine if a Sequence is Arithmetic

In the following exercises, determine if each sequence is arithmetic, and if so, indicate the common difference.

−7, −1, 5, 11, 17, 23, …

Answer

The sequence is arithmetic with common difference d=6.

12.R-263 §12.R source ↗

In the following exercises, write the first five terms of each arithmetic sequence with the given first term and common difference.

a1=5 and d=3

Answer

5, 8, 11, 14, 17

12.R-265 §12.R source ↗

In the following exercises, write the first five terms of each arithmetic sequence with the given first term and common difference.

a1=−13 and d=6

Answer

−13, −7, −1, 5, 11

12.R-267 §12.R source ↗

Find the General Term (nth Term) of an Arithmetic Sequence

In the following exercises, find the term described using the information provided.

Find the thirtieth term of a sequence where the first term is 16 and the common difference is −5.

Answer

−129

12.R-269 §12.R source ↗

In the following exercises, find the indicated term and give the formula for the general term.

Find the eighteenth term of a sequence where the fifth term is 12 and the common difference is seven.

Answer

a18=103. The general term is an=7n−23.

12.R-271 §12.R source ↗

In the following exercises, find the first term and common difference of the sequence with the given terms. Give the formula for the general term.

The fifth term is 17 and the fourteenth term is 53.

Answer

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

12.R-273 §12.R source ↗

Find the Sum of the First n Terms of an Arithmetic Sequence

In the following exercises, find the sum of the first 30 terms of each arithmetic sequence.

7, 4, 1, −2, −5, …

Answer

−1,095

12.R-275 §12.R source ↗

In the following exercises, find the sum of the first fifteen terms of the arithmetic sequence whose general term is given.

a n = 4 n + 7

Answer

585

12.R-277 §12.R source ↗

In the following exercises, find each sum.

∑ i = 1 50 ( 4 i − 5 )

Answer

4,850

12.R-279 §12.R source ↗

In the following exercises, find each sum.

∑ i = 1 35 ( i + 10 )

Answer

980

12.R-281 §12.R source ↗

Determine if a Sequence is Geometric

In the following exercises, determine if the sequence is geometric, and if so, indicate the common ratio.

5, 10, 15, 20, 25, 30, …

Answer

The sequence is not geometric.

12.R-283 §12.R source ↗

Determine if a Sequence is Geometric

In the following exercises, determine if the sequence is geometric, and if so, indicate the common ratio.

9, −18, 36, −72, 144, −288, …

Answer

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

12.R-285 §12.R source ↗

In the following exercises, write the first five terms of each geometric sequence with the given first term and common ratio.

a1=128 and r=14

Answer

128, 32, 8, 2, 1 2

12.R-287 §12.R source ↗

Find the General Term (nth Term) of a Geometric Sequence

In the following exercises, find the indicated term of a sequence where the first term and the common ratio is given.

Find a9 given a1=6 and r=2.

Answer

1,536

12.R-289 §12.R source ↗

In the following exercises, find the indicated term of the given sequence. Find the general term of the sequence.

Find a12 of the sequence, 6, −24, 96, −384, 1536, −6144, …

Answer

a12= −25, 165, 824. The general term is an= 6(−4)n−1.

12.R-291 §12.R source ↗

Find the Sum of the First n terms of a Geometric Sequence

In the following exercises, find the sum of the first fifteen terms of each geometric sequence.

−4, 8, −16, 32, −64, 128…

Answer

−43,692

12.R-293 §12.R source ↗

Find the Sum of the First n terms of a Geometric Sequence

In the following exercises, find the sum of the first fifteen terms of each geometric sequence.

3125, 625, 125, 25, 5, 1…

Answer

3906.25

12.R-295 §12.R source ↗

In the following exercises, find the sum

∑ i = 1 6 24 ( 1 2 ) i

Answer

189 8 = 23.625

12.R-297 §12.R source ↗

Find the Sum of an Infinite Geometric Series

In the following exercises, find the sum of each infinite geometric series.

49+ 7+ 1+ 1 7 + 1 49 + 1 343 + …

Answer

343 6 ≈ 57.167

12.R-299 §12.R source ↗

In the following exercises, write each repeating decimal as a fraction.

0. 36 —

Answer

4 11

12.R-301 §12.R source ↗

Apply Geometric Sequences and Series in the Real World

In the following exercises, solve the problem.

Adam just got his first full-time job after graduating from high school at age 17. He decided to invest $300 per month in an IRA (an annuity). The interest on the annuity is 7% which is compounded monthly. How much will be in Adam’s account when he retires at his sixty-seventh birthday?

Answer

$ 1,634,421.27

12.R-303 §12.R source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( x − y ) 4

Answer

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

12.R-305 §12.R source ↗

Use Pascal’s Triangle to Expand a Binomial

In the following exercises, expand each binomial using Pascal’s Triangle.

( 2 y − 3 ) 5

Answer

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

12.R-307 §12.R source ↗

Evaluate a Binomial Coefficient

In the following exercises, evaluate.


ⓐ (111)
ⓑ (1212)
ⓒ (130)
ⓓ (83)

Answer

ⓐ 11 ⓑ 1 ⓒ 1 ⓓ 56

12.R-309 §12.R source ↗

Evaluate a Binomial Coefficient

In the following exercises, evaluate.


ⓐ (11)
ⓑ (1515)
ⓒ (40)
ⓓ (112)

Answer

ⓐ 1 ⓑ 1 ⓒ 1 ⓓ 55

12.R-311 §12.R source ↗

Use the Binomial Theorem to Expand a Binomial

In the following exercises, expand each binomial, using the Binomial Theorem.

( t − 1 ) 9

Answer

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

12.R-313 §12.R source ↗

Use the Binomial Theorem to Expand a Binomial

In the following exercises, expand each binomial, using the Binomial Theorem.

( 4 x + 3 y ) 4

Answer

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

12.R-315 §12.R source ↗

In the following exercises, find the indicated term in the expansion of the binomial.

Seventh term of (a+b)9

Answer

84 a 3 b 6

12.R-317 §12.R source ↗

In the following exercises, find the coefficient of the indicated term in the expansion of the binomial.

y4 term of (y+3)6

Answer

135

12.R-319 §12.R source ↗

In the following exercises, find the coefficient of the indicated term in the expansion of the binomial.

a3b4 term of (2a+b)7

Answer

280

12.T-321 §12.T source ↗

In the following exercises, write the first five terms of the sequence whose general term is given.

a n = ( n + 2 ) ! ( n + 3 ) !

Answer

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

12.T-323 §12.T source ↗

In the following exercises, write the first five terms of the sequence whose general term is given.

Expand the partial sum and find its value. ∑i=14(−4)i

Answer

−4+ 16− 64+ 256= 204

12.T-325 §12.T source ↗

In the following exercises, write the first five terms of the sequence whose general term is given.

Write the first five terms of the arithmetic sequence with the given first term and common difference. a1=−13 and d=3

Answer

−13, −10, −7, −4, −1

12.T-327 §12.T source ↗

In the following exercises, write the first five terms of the sequence whose general term is given.

Find the twenty-third term of an arithmetic sequence whose seventh term is 11 and common difference is three. Then find a formula for the general term.

Answer

a23=59. The general term is an=3n−10.

12.T-329 §12.T source ↗

In the following exercises, write the first five terms of the sequence whose general term is given.

Find the sum of the first 25 terms of the arithmetic sequence, 5, 9, 13, 17, 21, …

Answer

1,325

12.T-331 §12.T source ↗

In the following exercises, write the first five terms of the sequence whose general term is given.

Find the sum. ∑i=140(5i−21)

Answer

3,260

12.T-333 §12.T source ↗

In the following exercises, determine if the sequence is arithmetic, geometric, or neither. If arithmetic, then find the common difference. If geometric, then find the common ratio.

324, 108, 36, 12, 4, 4 3 , …

Answer

The sequence is geometric with common ratio r=13.

12.T-335 §12.T source ↗

In the following exercises, determine if the sequence is arithmetic, geometric, or neither. If arithmetic, then find the common difference. If geometric, then find the common ratio.

In the geometric sequence whose first term and common ratio are a1=5 and r=4, find a11.

Answer

5,242,880

12.T-337 §12.T source ↗

In the following exercises, determine if the sequence is arithmetic, geometric, or neither. If arithmetic, then find the common difference. If geometric, then find the common ratio.

Find the sum of the first thirteen terms of the geometric sequence, 2, −6, 18, −54, 162, −486…

Answer

797,162

12.T-339 §12.T source ↗

In the following exercises, find the sum.

1− 1 5 + 1 25 − 1 125 + 1 625 − 1 3125 + …

Answer

5 6

12.T-341 §12.T source ↗

In the following exercises, find the sum.

Dave just got his first full-time job after graduating from high school at age 18. He decided to invest $450 per month in an IRA (an annuity). The interest on the annuity is 6% which is compounded monthly. How much will be in Adam’s account when he retires at his sixty-fifth birthday?

Answer

$ 1,409,344.19

12.T-343 §12.T source ↗

In the following exercises, find the sum.

Evaluate each binomial coefficient. ⓐ (81)
ⓑ (1616) ⓒ (120) ⓓ (106)

Answer

ⓐ 8 ⓑ 1 ⓒ 1 ⓓ 210

End of the book.

Problems and answers are adapted from Intermediate Algebra 2e by Lynn Marecek and Andrea Honeycutt Mathis, OpenStax, and are used under the CC BY-NC-SA 4.0 licence. Access for free at https://openstax.org/books/intermediate-algebra-2e/pages/1-introduction. Illustrations: Copyright Rice University, OpenStax, under CC BY-NC-SA 4.0 license. This adaptation is released under the same licence, is non-commercial, and is neither affiliated with nor endorsed by OpenStax or Rice University.