Sequences And Series; Summation Of A Series - Casio fx-9860GII Instructions Manual

Sequences and series

1.21 Summation of a series

Example 24
Find the sum of the fi rst 20 terms of the arithmetic sequence 4, 7, 10, 13, ...
The kth term of an arithmetic sequence is u
In this example u = 4, d = 3 and n = 20.
1
20
å
S 4 ( k 1)3
n
k 1
Press MENU . You will see the dialog box as shown on the right.
Choose 1: RUN·MAT and press
F4 F6
Press MATH |
The template matches the written Sigma formula.
Enter the variables, values and the function as they are written.
Use the keys to move around the template.
The sum of the terms of the sequence is 650.
Example 25
Find the sum of the fi rst 12 terms of the geometric sequence 3
The kth term of a geometric sequence is u
= 3, r = −
In the example u
1
Press MENU . You will see the dialog box as shown on the right.
Choose 1: RUN·MAT and press
Press F4 MATH | F6
The template matches the written Sigma formula.
Enter the variables, values and the function as they are written.
Use the keys to move around the template.
The sum of the terms of sequence is 2.25, to 3 signifi cant fi gures.
© Oxford University Press 2012: this may be reproduced for class use solely for the purchaser's institute
= u + (k − 1)d
k 1
EXE .
Σ(
F2
|
⋅ r
= u k−1
k 1
12
1
å
and n = 12.
S
n
3
k 1
EXE .
Σ(
| F2
1 1
− −
, 1 , , , ...
3 9
æ ö ÷
k 1
ç 1
÷
3 ç
ç è ÷
ø
3
Casio fx-9860GII
Using a graphic display calculator 25