Give an example of a function and a point x = a such that the limit of the function as approaches a exists but x = a is not in the domain of the function

Advanced Engineering Mathematics
10th Edition
ISBN:9780470458365
Author:Erwin Kreyszig
Publisher:Erwin Kreyszig
Chapter2: Second-order Linear Odes
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4.4

**Example of a Function with a Limit at a Point Not in Its Domain**

Consider a function where the limit exists as \( x \) approaches a certain point \( x = a \), but \( a \) is not included in the domain of the function. 

One common example is the function \( f(x) = \frac{\sin x}{x} \). Let's look at this function in detail. 

**Example:**

1. **Function Definition**: \( f(x) = \frac{\sin x}{x} \)

2. **Domain**: The function is not defined at \( x = 0 \) because attempting to evaluate \( \frac{\sin 0}{0} \) results in an undefined expression (division by zero).

3. **Limit at \( x = 0 \)**:
   - As \( x \to 0 \), the limit of \( f(x) = \frac{\sin x}{x} \) is known and proven to be \( 1 \).
   - \[
     \lim_{x \to 0} \frac{\sin x}{x} = 1
     \]
     
In this case, even though the limit of the function as \( x \) approaches 0 exists and is equal to 1, the function itself is not defined at \( x = 0 \). Thus, \( x = 0 \) is not in the domain of \( f(x) \). This illustrates a scenario where a function has a limit at a point that is not included in its domain.
Transcribed Image Text:**Example of a Function with a Limit at a Point Not in Its Domain** Consider a function where the limit exists as \( x \) approaches a certain point \( x = a \), but \( a \) is not included in the domain of the function. One common example is the function \( f(x) = \frac{\sin x}{x} \). Let's look at this function in detail. **Example:** 1. **Function Definition**: \( f(x) = \frac{\sin x}{x} \) 2. **Domain**: The function is not defined at \( x = 0 \) because attempting to evaluate \( \frac{\sin 0}{0} \) results in an undefined expression (division by zero). 3. **Limit at \( x = 0 \)**: - As \( x \to 0 \), the limit of \( f(x) = \frac{\sin x}{x} \) is known and proven to be \( 1 \). - \[ \lim_{x \to 0} \frac{\sin x}{x} = 1 \] In this case, even though the limit of the function as \( x \) approaches 0 exists and is equal to 1, the function itself is not defined at \( x = 0 \). Thus, \( x = 0 \) is not in the domain of \( f(x) \). This illustrates a scenario where a function has a limit at a point that is not included in its domain.
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