Proving f(z) is a continuous function in the entire complex plane

In summary, the conversation discusses proving the continuity of the function f(z) = Re(z) + Im(z) in the entire complex plane. It is mentioned that this requires showing that Re(z) and Im(z) are continuous. The conversation also suggests starting by writing z as x + iy and using the definition of continuity. The question is raised if the functions f(z) = x and f(z) = y are continuous, and the possibility of using the inequality |Re(z)| ≤ |z| is mentioned.
  • #1
lonewolf999
3
0

Homework Statement


Show that the function f(z) = Re(z) + Im(z) is continuous in the entire complex
plane.


Homework Equations





The Attempt at a Solution



I know that to prove f(z) is a continuous function i have to show that it is continuous at each part of its domain.

I take it that means i have to prove that Re(z) and Im(z) are continuous, however i have tried reading through my notes on how to do this and havn't been able to come up with a starting point.
 
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  • #2
Try writing out z as the usual combination of x + iy. Then what is Re(z) and Im(z)? Are these functions continuous?
 
  • #3
if i take z=x+iy, then Re(z)=x and Im(z)=y, however i can't finish it there.
 
  • #4
Is the function f(z) = x continuous? Is the function f(z) = y continuous? Start with the definition of continuity.
 
  • #5
Is it by some chance true that [tex]|Re(z)|\leq |z|[/tex]?
 

1. What is a continuous function?

A continuous function is a type of mathematical function that has a smooth and unbroken graph. This means that there are no sudden jumps or breaks in the graph, and it can be drawn without lifting your pen.

2. How do you prove that f(z) is a continuous function in the entire complex plane?

In order to prove that f(z) is a continuous function in the entire complex plane, we need to show that it is continuous at every point in the complex plane. This can be done by showing that the limit of f(z) as z approaches any point in the complex plane is equal to the value of f(z) at that point.

3. What is the importance of proving f(z) is a continuous function in the entire complex plane?

Proving that f(z) is a continuous function in the entire complex plane is important because it ensures that there are no sudden jumps or breaks in the graph of the function. This means that the function can be used to model real-world phenomena and make accurate predictions.

4. What techniques can be used to prove f(z) is a continuous function in the entire complex plane?

There are several techniques that can be used to prove that f(z) is a continuous function in the entire complex plane. These include using the definition of continuity, using theorems such as the Intermediate Value Theorem or the Extreme Value Theorem, and using properties of continuous functions such as continuity of addition, multiplication, and composition.

5. Can a function be continuous in one part of the complex plane but not in another?

Yes, a function can be continuous in one part of the complex plane but not in another. This means that the function may have sudden jumps or breaks in its graph in certain regions of the complex plane, but is still considered continuous overall. It is important to specify the domain of a function when discussing its continuity.

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