Find the sum of the following infinite geometric series, or state that it is not possible. 31 k 8

Algebra and Trigonometry (6th Edition)
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Author:Robert F. Blitzer
Publisher:Robert F. Blitzer
ChapterP: Prerequisites: Fundamental Concepts Of Algebra
Section: Chapter Questions
Problem 1MCCP: In Exercises 1-25, simplify the given expression or perform the indicated operation (and simplify,...
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**Problem Statement:**

Find the sum of the following infinite geometric series, or state that it is not possible.

\[
\sum_{k=1}^{\infty} 8 \left(\frac{-3}{4}\right)^k
\]

_To solve this problem:_

1. **Identify the First Term (a) and Common Ratio (r):**
   - The first term (a) can be identified as the first term of the series when \(k=1\).
   - The common ratio (r) is the factor by which each term of the series is multiplied to get the next term.

2. **Geometric Series Sum Formula for |r| < 1:**
   - For an infinite geometric series to have a sum, the absolute value of the common ratio |r| must be less than 1.
   - The sum \(S\) of an infinite geometric series is given by:
     
     \[
     S = \frac{a}{1 - r}
     \]
  
3. **Apply the Values:**
   - Here, the first term \(a_1 = 8 \left(\frac{-3}{4}\right)^1 = 8 \times \frac{-3}{4} = -6\)
   - The common ratio \(r = \frac{-3}{4}\)

4. **Check if |r| < 1:**
   - Here, \(|\frac{-3}{4}| = \frac{3}{4} < 1\)

5. **Calculate the Sum:**
   - Substitute the values into the formula:
     
     \[
     S = \frac{a}{1 - r} = \frac{-6}{1 - \left(\frac{-3}{4}\right)} = \frac{-6}{1 + \frac{3}{4}} = \frac{-6}{\frac{7}{4}} = -6 \times \frac{4}{7} = \frac{-24}{7}
     \]

Thus, the sum of the given infinite geometric series is:

\[
\boxed{\frac{-24}{7}}
\]
Transcribed Image Text:**Problem Statement:** Find the sum of the following infinite geometric series, or state that it is not possible. \[ \sum_{k=1}^{\infty} 8 \left(\frac{-3}{4}\right)^k \] _To solve this problem:_ 1. **Identify the First Term (a) and Common Ratio (r):** - The first term (a) can be identified as the first term of the series when \(k=1\). - The common ratio (r) is the factor by which each term of the series is multiplied to get the next term. 2. **Geometric Series Sum Formula for |r| < 1:** - For an infinite geometric series to have a sum, the absolute value of the common ratio |r| must be less than 1. - The sum \(S\) of an infinite geometric series is given by: \[ S = \frac{a}{1 - r} \] 3. **Apply the Values:** - Here, the first term \(a_1 = 8 \left(\frac{-3}{4}\right)^1 = 8 \times \frac{-3}{4} = -6\) - The common ratio \(r = \frac{-3}{4}\) 4. **Check if |r| < 1:** - Here, \(|\frac{-3}{4}| = \frac{3}{4} < 1\) 5. **Calculate the Sum:** - Substitute the values into the formula: \[ S = \frac{a}{1 - r} = \frac{-6}{1 - \left(\frac{-3}{4}\right)} = \frac{-6}{1 + \frac{3}{4}} = \frac{-6}{\frac{7}{4}} = -6 \times \frac{4}{7} = \frac{-24}{7} \] Thus, the sum of the given infinite geometric series is: \[ \boxed{\frac{-24}{7}} \]
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