6. Show that the sequence (5)" is Cauchy by using the Cauchy definition.

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### Problem Statement
**6. Show that the sequence \( \left( \frac{1}{2} \right)^n \) is Cauchy by using the Cauchy definition.**

### Detailed Explanation
In this problem, you are asked to prove that the sequence \( \left( \frac{1}{2} \right)^n \) is a Cauchy sequence. To do this, you need to use the Cauchy definition for a sequence.

### Cauchy Sequence Definition
A sequence \( (a_n) \) is said to be a Cauchy sequence if for every \( \epsilon > 0 \), there exists an integer \( N \) such that for all \( m, n \geq N \), the inequality \( |a_n - a_m| < \epsilon \) holds.

### Steps to Prove
1. **Identify the Sequence**: The sequence given is \( a_n = \left( \frac{1}{2} \right)^n \).
2. **Write the Cauchy Condition**: For every \( \epsilon > 0 \), find an integer \( N \) such that for all \( m, n \geq N \), \( | \left( \frac{1}{2} \right)^n - \left( \frac{1}{2} \right)^m | < \epsilon \).

### Solution Outline
1. Start by considering the absolute difference \( | a_n - a_m | = \left| \left( \frac{1}{2} \right)^n - \left( \frac{1}{2} \right)^m \right| \).
2. Without loss of generality, assume \( n \leq m \). Then rewrite the difference as \( \left| \left( \frac{1}{2} \right)^n - \left( \frac{1}{2} \right)^m \right| = \left( \frac{1}{2} \right)^n \left| 1 - \left( \frac{1}{2} \right)^{m-n} \right| \).
3. Notice that \( \left( \frac{1}{2} \right)^{m-n} \) is a positive number between 0 and 1, thus \( \left| 1 - \left( \frac{1}{
Transcribed Image Text:### Problem Statement **6. Show that the sequence \( \left( \frac{1}{2} \right)^n \) is Cauchy by using the Cauchy definition.** ### Detailed Explanation In this problem, you are asked to prove that the sequence \( \left( \frac{1}{2} \right)^n \) is a Cauchy sequence. To do this, you need to use the Cauchy definition for a sequence. ### Cauchy Sequence Definition A sequence \( (a_n) \) is said to be a Cauchy sequence if for every \( \epsilon > 0 \), there exists an integer \( N \) such that for all \( m, n \geq N \), the inequality \( |a_n - a_m| < \epsilon \) holds. ### Steps to Prove 1. **Identify the Sequence**: The sequence given is \( a_n = \left( \frac{1}{2} \right)^n \). 2. **Write the Cauchy Condition**: For every \( \epsilon > 0 \), find an integer \( N \) such that for all \( m, n \geq N \), \( | \left( \frac{1}{2} \right)^n - \left( \frac{1}{2} \right)^m | < \epsilon \). ### Solution Outline 1. Start by considering the absolute difference \( | a_n - a_m | = \left| \left( \frac{1}{2} \right)^n - \left( \frac{1}{2} \right)^m \right| \). 2. Without loss of generality, assume \( n \leq m \). Then rewrite the difference as \( \left| \left( \frac{1}{2} \right)^n - \left( \frac{1}{2} \right)^m \right| = \left( \frac{1}{2} \right)^n \left| 1 - \left( \frac{1}{2} \right)^{m-n} \right| \). 3. Notice that \( \left( \frac{1}{2} \right)^{m-n} \) is a positive number between 0 and 1, thus \( \left| 1 - \left( \frac{1}{
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