To prove that lim(x-7) 2x - 3= 11 using the ε- definition, we need there exists a 8 >0 such that if 0 < x - 7| <8, then |(2x-3) -11 | < | Given & > 0, we want to find a 8 >0 such that if 0 < x-7| <8, then [(2x-3) -11|

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
Section: Chapter Questions
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Did I do this proof correctly? 

### Proving the Limit Using the ε-δ Definition

To prove that \(\lim_{{x \to 7}} 2x - 3 = 11\) using the ε-δ definition, we need to show that for any given \( \varepsilon > 0 \), there exists a \( \delta > 0 \) such that if \( 0 < |x - 7| < \delta \), then \( |2x - 3 - 11| < \varepsilon \).

#### Step-by-Step Solution:

1. **Restate the Problem:**
   Given \( \varepsilon > 0 \), we want to find a \( \delta > 0 \) such that if \( 0 < |x - 7| < \delta \), then \( |2x - 3 - 11| < \varepsilon \).

2. **Simplify the Expression:**
   Let's work with the expression \(|2x - 3 - 11|\) and simplify it:
   \[
   |2x - 3 - 11| = |2x - 14|
   \]

3. **Finding an Upper Bound:**
   Now, we can try to find an upper bound for \( |2x - 14| \) based on a given \( \varepsilon \).

4. **Rewriting the Expression:**
   We can rewrite \( |2x - 14| \) as \( |2(x - 7)| \). Notice that when \( |x - 7| < 1 \), we have:
   \[
   |2(x - 7)| < 2
   \]

5. **Choosing \( \delta \):**
   So, if we choose \( \delta = 1 \), then for any \( 0 < |x - 7| < 1 \), we have \( |2x - 14| < 2 \).

6. **Proceed to Show \( |2x - 14| < \varepsilon \):**
   Now, we can proceed to show that \( |2x - 3 - 11| < \varepsilon \) when \( 0 < |x - 7| < \delta \):
   \[
   |2x - 14| = |2(x - 7)| < 2
   \]
   We can choose
Transcribed Image Text:### Proving the Limit Using the ε-δ Definition To prove that \(\lim_{{x \to 7}} 2x - 3 = 11\) using the ε-δ definition, we need to show that for any given \( \varepsilon > 0 \), there exists a \( \delta > 0 \) such that if \( 0 < |x - 7| < \delta \), then \( |2x - 3 - 11| < \varepsilon \). #### Step-by-Step Solution: 1. **Restate the Problem:** Given \( \varepsilon > 0 \), we want to find a \( \delta > 0 \) such that if \( 0 < |x - 7| < \delta \), then \( |2x - 3 - 11| < \varepsilon \). 2. **Simplify the Expression:** Let's work with the expression \(|2x - 3 - 11|\) and simplify it: \[ |2x - 3 - 11| = |2x - 14| \] 3. **Finding an Upper Bound:** Now, we can try to find an upper bound for \( |2x - 14| \) based on a given \( \varepsilon \). 4. **Rewriting the Expression:** We can rewrite \( |2x - 14| \) as \( |2(x - 7)| \). Notice that when \( |x - 7| < 1 \), we have: \[ |2(x - 7)| < 2 \] 5. **Choosing \( \delta \):** So, if we choose \( \delta = 1 \), then for any \( 0 < |x - 7| < 1 \), we have \( |2x - 14| < 2 \). 6. **Proceed to Show \( |2x - 14| < \varepsilon \):** Now, we can proceed to show that \( |2x - 3 - 11| < \varepsilon \) when \( 0 < |x - 7| < \delta \): \[ |2x - 14| = |2(x - 7)| < 2 \] We can choose
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