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Graphing Calculator Activity for use with Lesson 11.1
ACTIVITY 11.1
Using Technology
Working with Sequences
You can use a graphing calculator to find the terms of a sequence, graph a
sequence, and find the sum of a series.
EXAMPLE
Use a graphing calculator to perform the following.
• Find the first eight terms of the sequence an = 3n º 1.
• Graph the sequence.
• Find the sum of the first eight terms of the sequence.
SOLUTION
2
1 Put the graphing calculator in
INT
STUDENT HELP
NE
ER T
KEYSTROKE
HELP
See keystrokes for
several models of
calculators at
www.mcdougallittell.com
Sequence mode and Dot mode. Enter
the sequence. Note that the calculator
uses u(n) rather than an.
Use the Table feature to view the
terms of the sequence. The first eight
terms are 2, 5, 8, 11, 14, 17, 20, and 23.
Min=1
u( )=3 -1
u( Min)=
v( )=
v( Min)=
w( )=
w( Min)=
=1
4
3 Set the viewing window so that
1 ≤ n ≤ 8, 1 ≤ x ≤ 8, and
0 ≤ y ≤ 25. Graph the sequence.
Use the Trace feature to view the
terms of the sequence.
Use the Summation feature to find
the sum of the first eight terms
of the sequence. The screen shows
that the sum is 100.
sum(seq(3 -1, ,1,
8,1))
100
u=3 -1
=4
X=4
u( )
2
5
8
11
14
1
2
3
4
5
Y=11
EXERCISES
Use a graphing calculator to (a) find the first ten terms of the sequence, (b) graph
the sequence, and (c) find the sum of the first ten terms of the sequence.
1. an = 2n + 3
658
2. an = 4(n + 1)
1 n
3. an = 50 º 2n
4. an = 2n º 1
5. an = 2
6. an = 2 + n2
7. an = 3 • 4n º 2
8. an = 10n + 2
1
9. an = + n3
3
Chapter 11 Sequences and Series