Is this delta epsilon proof correct?

Your steps are clear and concise, and you have correctly used the definition of a limit to prove the statement. Well done! In summary, to show that Re(z) approaches Re(z0) as z approaches z0, we choose delta = epsilon and use the definition of a limit to show that |Re(z) - Re(z0)| is less than epsilon if |z - z0| is less than delta.
  • #1
tylerc1991
166
0

Homework Statement



Show that Re(z) -> Re(z0) as z -> z0

The Attempt at a Solution



let epsilon > 0, choose delta = epsilon, so

|Re(z) - Re(z0)| = |(z + z')/2 - (z0 + z0')/2| (where z' and z0' are the complex conjugates)

|(z + z')/2 - (z0 + z0')/2| = |(z - z0 + z' - z0')/2| < |z - z0|/2 + |z' - z0'|/2

|z - z0|/2 + |z' - z0'|/2 = |z - z0| (since |z' - z0'| = |z - z0|)

|z - z0| < epsilon if 0 < |z - z0| < delta

Did I do this correctly? Are there any skipped steps? Thank you for your feedback!
 
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  • #2
Your concluding line should be:

|Re(z) - Re(z0)| < ε if 0 < |z - z0| < δ

Otherwise, it looks good.
 

FAQ: Is this delta epsilon proof correct?

What is a delta epsilon proof?

A delta epsilon proof is a type of mathematical proof used to formally prove the limit of a function. It involves using the concepts of delta (change in x) and epsilon (tolerance) to show that as x approaches a certain value, the corresponding values of the function also approach a certain value.

How do you know if a delta epsilon proof is correct?

A delta epsilon proof is considered correct if it follows the proper structure and logic of the proof. This includes clearly defining the delta and epsilon values, showing the relationship between them, and using the definition of a limit to prove the desired result. Additionally, the proof should be easily reproducible and not contain any errors or contradictions.

Can a delta epsilon proof be used for all functions?

Yes, a delta epsilon proof can be used for any function as long as the function has a limit. However, some functions may be more difficult to prove using the delta epsilon method, and other proof techniques may be more appropriate.

Why is a delta epsilon proof important?

A delta epsilon proof is important because it provides a rigorous and formal way to prove the limit of a function. It is widely used in advanced mathematics and sciences, and is essential in understanding the underlying principles of calculus and analysis.

How can I improve my skills in writing delta epsilon proofs?

One way to improve your skills in writing delta epsilon proofs is to practice regularly. You can also seek feedback from others or study examples of well-written proofs. Additionally, understanding the concepts and logic behind the proof is crucial in being able to write a correct and convincing proof.

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