Math Problem Statement

Consider the finite geometric series.

βˆ‘π‘˜=362(3)π‘˜βˆ’1k=3βˆ‘6​2(3)kβˆ’1​List each of the 44​ terms from the expanded form of the geometric series. Separate each term with a comma.

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Evaluate the series.

Solution

To list each term of the finite geometric series and then evaluate it, we first identify the terms using the series formula:

βˆ‘k=362β‹…3kβˆ’1\sum_{k=3}^{6} 2 \cdot 3^{k-1}

The general term of the series is given by aβ‹…rkβˆ’1a \cdot r^{k-1}, where a=2a = 2 (the first term when k=3k = 3), r=3r = 3 (the common ratio), and kk starts from 3 and goes to 6.

Listing the Terms

To find each term, substitute the values of kk from 3 to 6:

  • For k=3k = 3: 2β‹…33βˆ’1=2β‹…32=2β‹…9=182 \cdot 3^{3-1} = 2 \cdot 3^2 = 2 \cdot 9 = 18
  • For k=4k = 4: 2β‹…34βˆ’1=2β‹…33=2β‹…27=542 \cdot 3^{4-1} = 2 \cdot 3^3 = 2 \cdot 27 = 54
  • For k=5k = 5: 2β‹…35βˆ’1=2β‹…34=2β‹…81=1622 \cdot 3^{5-1} = 2 \cdot 3^4 = 2 \cdot 81 = 162
  • For k=6k = 6: 2β‹…36βˆ’1=2β‹…35=2β‹…243=4862 \cdot 3^{6-1} = 2 \cdot 3^5 = 2 \cdot 243 = 486

The terms are: 18, 54, 162, 486

Evaluating the Series

To evaluate the series, we sum the terms:

S=18+54+162+486S = 18 + 54 + 162 + 486

Let's calculate the sum.The terms of the geometric series are:

18, 54, 162, 486

The sum of these terms is:

S=720S = 720

Would you like any further details or explanations?

Here are some related questions to consider:

  1. What is the formula for the nn-th term of a geometric series?
  2. How does the common ratio affect the growth rate of the terms in a geometric series?
  3. What happens to the series sum if the number of terms is increased indefinitely?
  4. Can a geometric series have negative terms? If so, how does this affect the sum?
  5. What is the difference between a finite and infinite geometric series?
  6. How do you determine if a geometric series converges or diverges?
  7. What are some real-world applications of geometric series?
  8. How does changing the first term aa affect the series?

Tip: In geometric series, understanding the common ratio's role can provide insights into the series' behavior and sum calculation.

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Math Problem Analysis

Mathematical Concepts

Geometric Series

Formulas

Sum of a finite geometric series
General term of a geometric series

Theorems

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Suitable Grade Level

High School