7. Evaluate each geometric series or state that it diverges. Provide reasons for your conclusion. k 6 (@) Σ (-3)* k=0 (b) 5,6* 7k k=0

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### Series Evaluation in Geometric Sequences

**Problem 7**: Evaluate each geometric series or state that it diverges. Provide reasons for your conclusion.

#### (a) 
\[ 
\sum_{k=0}^{\infty} \left( -\frac{6}{5} \right)^k 
\]

#### (b)
\[ 
\sum_{k=0}^{\infty} \frac{5 \cdot 6^k}{7^k} 
\]

_For each series, determine if it converges or diverges and justify your reasoning:_

---

### Explanation:

#### Convergence and Divergence of Geometric Series

A geometric series:

\[ 
\sum_{k=0}^{\infty} ar^k 
\]

1. **Converges** if \( |r| < 1 \). The series sum is given by: 

\[ 
\sum_{k=0}^{\infty} ar^k = \frac{a}{1-r} 
\]

2. **Diverges** if \( |r| \geq 1 \).

#### Analysis for (a)
\[ 
\sum_{k=0}^{\infty} \left( -\frac{6}{5} \right)^k 
\]

Here, \( a = 1 \) and \( r = -\frac{6}{5} \).

- Since \( |r| = \left| -\frac{6}{5} \right| = \frac{6}{5} > 1 \), the series diverges.

#### Analysis for (b)
\[ 
\sum_{k=0}^{\infty} \frac{5 \cdot 6^k}{7^k} 
\]

Rewrite the given series:
\[ 
\sum_{k=0}^{\infty} 5 \left( \frac{6}{7} \right)^k 
\]

Here, \( a = 5 \) and \( r = \frac{6}{7} \).

- Since \( |r| = \left| \frac{6}{7} \right| = \frac{6}{7} < 1 \), the series converges.
- The sum of the series is: 

\[ 
\sum_{k=0}^{\infty} 5 \left( \frac{6}{7}
Transcribed Image Text:### Series Evaluation in Geometric Sequences **Problem 7**: Evaluate each geometric series or state that it diverges. Provide reasons for your conclusion. #### (a) \[ \sum_{k=0}^{\infty} \left( -\frac{6}{5} \right)^k \] #### (b) \[ \sum_{k=0}^{\infty} \frac{5 \cdot 6^k}{7^k} \] _For each series, determine if it converges or diverges and justify your reasoning:_ --- ### Explanation: #### Convergence and Divergence of Geometric Series A geometric series: \[ \sum_{k=0}^{\infty} ar^k \] 1. **Converges** if \( |r| < 1 \). The series sum is given by: \[ \sum_{k=0}^{\infty} ar^k = \frac{a}{1-r} \] 2. **Diverges** if \( |r| \geq 1 \). #### Analysis for (a) \[ \sum_{k=0}^{\infty} \left( -\frac{6}{5} \right)^k \] Here, \( a = 1 \) and \( r = -\frac{6}{5} \). - Since \( |r| = \left| -\frac{6}{5} \right| = \frac{6}{5} > 1 \), the series diverges. #### Analysis for (b) \[ \sum_{k=0}^{\infty} \frac{5 \cdot 6^k}{7^k} \] Rewrite the given series: \[ \sum_{k=0}^{\infty} 5 \left( \frac{6}{7} \right)^k \] Here, \( a = 5 \) and \( r = \frac{6}{7} \). - Since \( |r| = \left| \frac{6}{7} \right| = \frac{6}{7} < 1 \), the series converges. - The sum of the series is: \[ \sum_{k=0}^{\infty} 5 \left( \frac{6}{7}
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