![logo](logoAlgebra2.gif)
Evaluating Summation Notation
(Function Mode)
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A shorthand notation is used to represent sums with more than a few
terms. This shorthand notation uses the Greek letter sigma
(which denotes sum). If we have a rule such as f (n)
which assigns the value f (n) to each integer n in the set of integers {j, j+1, j+2, ... k},
we can represent the sum as:
=
On the graphing calculator:
We will be using the sum feature and the seq feature to work with a general
summation.
On the
calculator, we will interpret a summation as follows:
![3](summat10.gif)
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2nd STAT (LIST) → MATH
#5 sum
![4](summat18.gif)
The format for sum is sum( list )
where list will be the terms of
the rule
.
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2nd STAT (LIST) →
OPS Choose #5 seq(
![5](sequen21.gif)
The format for seq: expression,
variable,
starting value, ending value, increment.
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While sequences have a domain of
natural numbers, {1, 2, 3, 4, ...}, in Func mode, the sequence command will
accept integer domain values less than one. (In Seq mode, however, the sequence command will accept only
integer domain values of 1 or greater.)
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(For ease of entry, X was used as the variable in both examples above.
If you wish to use the designated variable, type it into the
calculator using the alpha
key.)
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Summations and Sequences: |
Sums, such as ,
where j = 1, may represent the summation of a sequence, called
a series.
![77](ag00092_.gif) |
Remember, sequences have a domain
of natural numbers, {1, 2, 3, 4, ...}.
In the sequence related
problems below, the starting
value in the summation will be greater than or equal to 1.
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Again, we will be using the sum and seq features of the calculator to find the summations. The
summation is interpreted as:
![25](summat3.gif)
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2nd STAT (LIST) → MATH
#5 sum
![24](summat18.gif) |
2nd STAT (LIST) →
OPS Choose #5 seq(
![26](sequen21.gif) |
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Example 3:
Evaluate: ![27](summat4.gif)
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![28](summat5.gif)
This example uses x as the variable,
instead of using j. The x is simply
easier to enter into the calculator.
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Example
4:
Evaluate: ![29](summat6.gif) |
![](summat7.gif)
This example uses n as the variable -- obtained by engaging the
alpha key.
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![divider](../TIGraphics/tidivider.gif)
Finding Your Way Around TABLE of
CONTENTS
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