Algebra 2

Prentice Hall, Basia Kennedy, Dan Ramirez

Chapter 11

Sequences And Series

Educators

DF
AG
sw

Problem 1

Describe each pattern formed. Find the next three terms.
$$
80,77,74,71,68, \dots
$$

DF
Daisy F.
Numerade Educator

Problem 2

Describe each pattern formed. Find the next three terms.
$$
4,8,16,32,64, \dots
$$

Susmith B.
Numerade Educator

Problem 3

Describe each pattern formed. Find the next three terms.
$$
0,3,7,12,18, \dots
$$

AG
Ankit G.
Numerade Educator

Problem 4

Describe each pattern formed. Find the next three terms.
$$
1,4,7,10,13, \dots
$$

Susmith B.
Numerade Educator

Problem 5

Describe each pattern formed. Find the next three terms.
$$
100,10,1,0.1,0.01, \dots
$$

sw
Sarah W.
Numerade Educator

Problem 6

Describe each pattern formed. Find the next three terms.
$$
\frac{1}{2}, \frac{1}{4}, \frac{1}{8}, \frac{1}{16}, \frac{1}{32}, \dots
$$

Susmith B.
Numerade Educator

Problem 7

Describe each pattern formed. Find the next three terms.
$$
4,-8,16,-32,64, \ldots
$$

DF
Daisy F.
Numerade Educator

Problem 8

Describe each pattern formed. Find the next three terms.
$$
1,2,6,24,120, \dots
$$

Susmith B.
Numerade Educator

Problem 9

Describe each pattern formed. Find the next three terms.
$$
0,1,0, \frac{1}{3}, 0, \frac{1}{5}, \dots
$$

DF
Daisy F.
Numerade Educator

Problem 10

Fractal Geometry Draw the first four figures of the sequence described.
_____ is replaced by

AG
Ankit G.
Numerade Educator

Problem 11

Fractal Geometry Draw the first four figures of the sequence described.
(TRIANGLE NOT COPY) is replaced by (TRIANGLE NOT COPY)

AG
Ankit G.
Numerade Educator

Problem 12

Write a recursive formula for each sequence. Then find the next term.
$$
-2,-1,0,1,2, \ldots
$$

Susmith B.
Numerade Educator

Problem 13

Write a recursive formula for each sequence. Then find the next term.
$$
43,41,39,37,35, \ldots
$$

DF
Daisy F.
Numerade Educator

Problem 14

Write a recursive formula for each sequence. Then find the next term.
$$
40,20,10,5, \frac{5}{2}, \dots
$$

Susmith B.
Numerade Educator

Problem 15

Write a recursive formula for each sequence. Then find the next term.
$$
6,1,-4,-9, \dots
$$

DF
Daisy F.
Numerade Educator

Problem 16

Write a recursive formula for each sequence. Then find the next term.
$$
144,36,9, \frac{9}{4}, \dots
$$

Susmith B.
Numerade Educator

Problem 17

Write a recursive formula for each sequence. Then find the next term.
$$
\frac{1}{2}, \frac{1}{4}, \frac{1}{8}, \frac{1}{16}, \frac{1}{32}, \dots
$$

DF
Daisy F.
Numerade Educator

Problem 18

Write an explicit formula for each sequence. Then find $a_{12}$
$$
4,5,6,7,8, \dots
$$

Susmith B.
Numerade Educator

Problem 19

Write an explicit formula for each sequence. Then find $a_{12}$
$$
\frac{1}{2}, \frac{1}{3}, \frac{1}{4}, \frac{1}{5}, \frac{1}{6}, \dots
$$

DF
Daisy F.
Numerade Educator

Problem 20

Write an explicit formula for each sequence. Then find $a_{12}$
$$
4,7,10,13,16, \dots
$$

Susmith B.
Numerade Educator

Problem 21

Write an explicit formula for each sequence. Then find $a_{12}$
$$
3,7,11,15,19, \ldots
$$

DF
Daisy F.
Numerade Educator

Problem 22

Write an explicit formula for each sequence. Then find $a_{12}$
$$
-2 \frac{1}{2},-2,-1 \frac{1}{2},-1, \ldots
$$

Susmith B.
Numerade Educator

Problem 23

Write an explicit formula for each sequence. Then find $a_{12}$
$$
2,5,10,17,26, \dots
$$

DF
Daisy F.
Numerade Educator

Problem 24

Decide whether each formula is explicit or recursive. Then find the first five terms of each sequence.
$$
a_{n}=2 a_{n-1}+3, \text { where } a_{1}=3
$$

Susmith B.
Numerade Educator

Problem 25

Decide whether each formula is explicit or recursive. Then find the first five terms of each sequence.
$$
a_{n}=\frac{1}{2}(n)(n-1)
$$

DF
Daisy F.
Numerade Educator

Problem 26

Decide whether each formula is explicit or recursive. Then find the first five terms of each sequence.
$$
(n-5)(n+5)=a_{n}
$$

Susmith B.
Numerade Educator

Problem 27

Decide whether each formula is explicit or recursive. Then find the first five terms of each sequence.
$$
a_{n}=-3 a_{n-1}, \text { where } a_{1}=-2
$$

DF
Daisy F.
Numerade Educator

Problem 28

Decide whether each formula is explicit or recursive. Then find the first five terms of each sequence.
$$
a_{n}=-4 n^{2}-2
$$

Susmith B.
Numerade Educator

Problem 29

Decide whether each formula is explicit or recursive. Then find the first five terms of each sequence.
$$
a_{n}=2 n^{2}+1
$$

DF
Daisy F.
Numerade Educator

Problem 30

Decide whether each formula is explicit or recursive. Then find the first five terms of each sequence.
$$
a_{n}=5 n
$$

Susmith B.
Numerade Educator

Problem 31

Decide whether each formula is explicit or recursive. Then find the first five terms of each sequence.
$$
a_{n}=a_{n-1}-17, \text { where } a_{1}=340
$$

DF
Daisy F.
Numerade Educator

Problem 32

Entertainment Suppose you are building a tower of cards with levels as displayed below. Complete the
table, assuming the pattern continues.

Susmith B.
Numerade Educator

Problem 33

Find the next two terms in each sequence. Write a formula for the $n$ th term. Identify each formula as explicit or recursive.
$$
5,8,11,14,17, \dots
$$

DF
Daisy F.
Numerade Educator

Problem 34

Find the next two terms in each sequence. Write a formula for the $n$ th term. Identify each formula as explicit or recursive.
$$
3,6,12,24,48, \dots
$$

Susmith B.
Numerade Educator

Problem 35

Find the next two terms in each sequence. Write a formula for the $n$ th term. Identify each formula as explicit or recursive.
$$
1,8,27,64,125, \dots
$$

DF
Daisy F.
Numerade Educator

Problem 36

Find the next two terms in each sequence. Write a formula for the $n$ th term. Identify each formula as explicit or recursive.
$$
4,16,64,256,1024, \dots
$$

Susmith B.
Numerade Educator

Problem 37

Find the next two terms in each sequence. Write a formula for the $n$ th term. Identify each formula as explicit or recursive.
$$
49,64,81,100,121, \ldots
$$

DF
Daisy F.
Numerade Educator

Problem 38

Find the next two terms in each sequence. Write a formula for the $n$ th term. Identify each formula as explicit or recursive.
$$
-1,1,-1,1,-1,1, \dots
$$

Susmith B.
Numerade Educator

Problem 39

Find the next two terms in each sequence. Write a formula for the $n$ th term. Identify each formula as explicit or recursive.
$$
-16,-8,-4,-2, \ldots
$$

DF
Daisy F.
Numerade Educator

Problem 40

Find the next two terms in each sequence. Write a formula for the $n$ th term. Identify each formula as explicit or recursive.
$$
-75,-68,-61,-54, \dots
$$

Susmith B.
Numerade Educator

Problem 41

Find the next two terms in each sequence. Write a formula for the $n$ th term. Identify each formula as explicit or recursive.
$$
21,13,5,-3, \dots
$$

DF
Daisy F.
Numerade Educator

Problem 42

Suppose the cartoon at the right included one sheep to the left and another sheep to the right of the three shown. What "names" would you give these sheep?

Susmith B.
Numerade Educator

Problem 43

Writing Explain the difference between a recursive formula and an explicit formula.

DF
Daisy F.
Numerade Educator

Problem 44

a. Open-Ended Write four terms of a sequence of numbers that you can describe both recursively and explicitly.
b. Write a recursive formula and an explicit formula for your sequence.
c. Find the 20 th term of the sequence by evaluating one of your formulas. Use the other formula to check your work.

Susmith B.
Numerade Educator

Problem 45

Use the given rule to write the $4 \mathrm{th}, 5 \mathrm{th}, 6 \mathrm{th},$ and 7 th terms of each sequence.
$$
a_{1}=-1, a_{n}=a_{n-1}+n^{2}
$$

DF
Daisy F.
Numerade Educator

Problem 46

Use the given rule to write the $4 \mathrm{th}, 5 \mathrm{th}, 6 \mathrm{th},$ and 7 th terms of each sequence.
$$
a_{1}=-2, a_{n}=3\left(a_{n-1}+2\right)
$$

Susmith B.
Numerade Educator

Problem 47

Use the given rule to write the $4 \mathrm{th}, 5 \mathrm{th}, 6 \mathrm{th},$ and 7 th terms of each sequence.
$$
a_{n}=(n+1)^{2}
$$

DF
Daisy F.
Numerade Educator

Problem 48

Use the given rule to write the $4 \mathrm{th}, 5 \mathrm{th}, 6 \mathrm{th},$ and 7 th terms of each sequence.
$$
a_{n}=2(n-1)^{3}
$$

Susmith B.
Numerade Educator

Problem 49

Use the given rule to write the $4 \mathrm{th}, 5 \mathrm{th}, 6 \mathrm{th},$ and 7 th terms of each sequence.
$$
a_{n}=\frac{n^{2}}{n+1}
$$

DF
Daisy F.
Numerade Educator

Problem 50

Use the given rule to write the $4 \mathrm{th}, 5 \mathrm{th}, 6 \mathrm{th},$ and 7 th terms of each sequence.
$$
a_{n}=\frac{n+1}{n+2}
$$

Susmith B.
Numerade Educator

Problem 51

Geometry Suppose you are stacking boxes in levels that form squares. The numbers of boxes in successive levels form a sequence. The figure at the left shows the top four levels as viewed from above.
a. How many boxes of equal size would you need for the next lower lever level?
b. How many boxes of equal size would you need to add three levels?
c. Suppose you are stacking a total of 285 boxes. How many levels will you have?

AG
Ankit G.
Numerade Educator

Problem 52

Use each recursive formula to write an explicit formula for the sequence.
$$
a_{1}=10, a_{n}=2 a_{n-1}
$$

Susmith B.
Numerade Educator

Problem 53

Use each recursive formula to write an explicit formula for the sequence.
$$
a_{1}=-5, a_{n}=a_{n-1}-1
$$

DF
Daisy F.
Numerade Educator

Problem 54

Use each recursive formula to write an explicit formula for the sequence.
$$
a_{1}=-2, a_{n}=\frac{1}{2} a_{n-1}
$$

Susmith B.
Numerade Educator

Problem 55

Use each recursive formula to write an explicit formula for the sequence.
$$
a_{1}=1, a_{n}=a_{n-1}+4
$$

DF
Daisy F.
Numerade Educator

Problem 56

Finance Use the information in the ad.
a. Suppose you start a savings account at Mun e-Bank. Write both a recursive formula and an explicit formula for the amount of money you would have in the bank at the end of any week.
b. How much money would you have in the bank after four weeks?
c. Assume the bank pays interest every four weeks. To calculate your interest, multiply the balance at the end of the four weeks by 0.005. Then add that much to your account on the last day of the four-week period. Write a recursive formula for the amount of money you have after each interest payment.
d. Critical Thinking What is the bank's annual interest rate?

Susmith B.
Numerade Educator

Problem 57

Geometry The triangular numbers form a sequence. The diagram represents the first three triangular numbers: $1,3,$ and $6 .$
a. Find the fifth and sixth triangular numbers.
b. Write a recursive formula for the $n$ th triangular number.
c. Is the explicit formula $a_{n}=\frac{1}{2}\left(n^{2}+n\right)$ the correct formula for this sequence? How do you know?

AG
Ankit G.
Numerade Educator

Problem 58

What is the difference between the third term in the sequence whose recursive formula is $a_{1}=-5, a_{n}=2 a_{n-1}+1$ and the third term in the sequence whose recursive formula is $a_{1}=-3, a_{n}=-a_{n-1}+3 ?$
$$
\begin{array}{lllll}{\text { A. } 2} & {\text { B. } 14} & {\text { C. } 20} & {\text { D. } 32}\end{array}
$$

Susmith B.
Numerade Educator

Problem 59

What is a recursive formula for the sequence whose explicit formula is $a_{n}=(n+1)^{2} ?$
F. $a_{1}=1, a_{n}=\left(a_{n-1}+1\right)^{2}$
H. $a_{1}=n, a_{n}=a_{n-1}+n$
G. $a_{1}=4, a_{n}=\left(\sqrt{a_{n-1}}+1\right)^{2}$
J. $a_{1}=n^{2}, a_{n}=\left(a_{n}-1\right)^{2}+1$

AG
Ankit G.
Numerade Educator

Problem 60

Use the figure below for Exercises $60-62$
(GRAPH NOT COPY)
How many $1 \times 1$ squares are in the sixth term of the sequence?
$$\begin{array}{llll}{\text { A. } 21} & {\text { B. } 36} & {\text { C. } 91} & {\text { D. } 441}\end{array}$$

Susmith B.
Numerade Educator

Problem 61

Use the figure below for Exercises $60-62$
(GRAPH NOT COPY)
Which expressions represent the first three terms of the sequence?
$$\begin{array}{ll}{\text { F. } 1^{2}, 2^{2}, 3^{2}, \ldots} & {\text { G. } 1,1+2,1+2+3, \ldots} \\ {\text { H. } 1^{2},(1+2)^{2},(1+2+3)^{2}, \ldots} & {\text { J. } 1^{2}, 1^{2}+2^{2}, 1^{2}+2^{2}+3^{2}, \ldots}\end{array}$$

AG
Ankit G.
Numerade Educator

Problem 62

Use the figure below for Exercises $60-62$
(GRAPH NOT COPY)
Write a recursive formula for the sequence in the figure above. Explain your reasoning.

Susmith B.
Numerade Educator

Problem 63

The graph of each equation is translated 2 units left and 3 units down. Write each new equation.
$$
(x+2)^{2}+(y-1)^{2}=5
$$

AG
Ankit G.
Numerade Educator

Problem 64

The graph of each equation is translated 2 units left and 3 units down. Write each new equation.
$$
\frac{(x-1)^{2}}{36}+\frac{(y-1)^{2}}{36}=1
$$

Susmith B.
Numerade Educator

Problem 65

Each point is from an inverse variation. Write an equation to model the data.
$$
(1,20)
$$

DF
Daisy F.
Numerade Educator

Problem 66

Each point is from an inverse variation. Write an equation to model the data.
$$
(5,2)
$$

Susmith B.
Numerade Educator

Problem 67

Each point is from an inverse variation. Write an equation to model the data.
$$
(9,13)
$$

DF
Daisy F.
Numerade Educator

Problem 68

Each point is from an inverse variation. Write an equation to model the data.
$$
(-3,-9)
$$

Susmith B.
Numerade Educator

Problem 69

Each point is from an inverse variation. Write an equation to model the data.
$$
(2,5)
$$

DF
Daisy F.
Numerade Educator

Problem 70

Each point is from an inverse variation. Write an equation to model the data.
$$
(-6,-12)
$$

Susmith B.
Numerade Educator

Problem 71

Each point is from an inverse variation. Write an equation to model the data.
$$
\left(\frac{1}{2},-\frac{1}{2}\right)
$$

DF
Daisy F.
Numerade Educator

Problem 72

Each point is from an inverse variation. Write an equation to model the data.
$$
(-10,-10)
$$

Susmith B.
Numerade Educator