How does ε disappear from the equation?

[Tomtam]

(edited by mentor to remove the boldness of the text)

how does ε disappear from the equation (5.197) ,if we take limit ε to zero?

 

[jedishrfu]

Welcome to PF!

There's not enough context to answer your question.

What does epsilon represent? is it part of a limit where epsilon goes to zero?

I didn't see any limit mentioned in the photo but that might explain why the epsilon term is removed.

 

[fresh_42]

how does ε disappear from the equation (5.197) ,if we take limit ε to zero?

Let me first clarify something: Am I right, that you expect more effort made in an answer than you spent to prepare your question? And as if this wasn't enough, you yell at those who are willing to deal with your question?

 

[Tomtam]

I'm sorry. More details. My question is about the integral I- . I have to make it approach positive x-axis from below, so why epsilon has to approach zero.

 

[Tomtam]

I'm sorry. More details. My question is about the integral I- . I have to make it approach positive x-axis from below, so why epsilon has to approach zero.

 

[jedishrfu]

So $i \epsilon$ is the imaginary component of the complex number $(x +i \epsilon)$ ?

 

[Tomtam]

So $i \epsilon$ is the imaginary component of the complex number $(x +i \epsilon)$ ?

yes

 

[jedishrfu]

Okay, I think @fresh_42 is better equipped to answer this.

One thing I'd like to point out here is that its bad form to write your question in bold lettering (or capitalized lettering) as it is seen as yelling by readers of your post.

Second thing is that you need to provide the context right up front as we don't know where you are coming from and then have to ask delaying a good response to your question.

Third things is you need to write your post in Latex instead of posting poor quality phone photos where its somewhat hard to read. Also it would be helpful if you used the homework template and tell us what level of math you are studying and what book you are using.