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# Sequences and means

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1. Find the sum of the finite geometric series to three decimal places.

9 n
Σ - 3(0.5)
n=3

2. Write the first 5 terms of the specified sequence. Determine whether the sequence is arithmetic. If it is, find the common difference.
Problem is "a(sub n)" = "1 over n+3"
a = _1_
n n+3

3. Find the sum of the first 14 terms of the arithmetic sequence, if the first term is -4 and the common difference is 5.

4. Find three arithmetic means between -5 and -37.

5. Determine which of the four sequences below are geometric.
7,14,28,56,112,...
7,1,-5,-11,-17,...
7,8,9,11,12,...
7,-14,28,-56,112,...

https://brainmass.com/math/algebra/sequence-arithmetic-finite-series-91322

#### Solution Preview

1. Find the sum of the finite geometric series to three decimal places.

9 n
Σ - 3(0.5)
n=3

By a formula , we have

9 n
Σ - 3(0.5)
n=3
= .............Take out a factor (-3)
= ........... Take out a factor (0.5)^3

.............Apply the formula with r=0.5 and n=6

2. Write the first 5 terms of the specified sequence. Determine whether the sequence is arithmetic. If it is, find the common difference.
...

#### Solution Summary

The problems in this set include geometric and arithmetic sequences and means. Which of the sequences are geometric are determined.

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