Can anyone tell me why this limit doesn't exist

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In summary, the limit of the complex function f(z) = \frac{\overline{z}}{z} as z tends to zero in ℂ is undefined because the value of the limit depends on the approach used. Different approaches yield different answers, indicating that the limit does not exist.
  • #1
blahblah8724
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The limit of the complex function,

[itex] f(z) = \frac{\overline{z}}{z}[/itex] as z tends to zero, where z is in ℂ

This is 1 when z is real and -1 when z is imaginary... but when z is complex??
 
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  • #2
The limit depends crucially from how you approach it. If you approach it vertically then it's -1. When you approach it horizonally, then it's 1.

If you approach it from the line x=y, then it's

[tex]\lim_{x\rightarrow 0}{\frac{x-ix}{x+ix}}=\frac{1-i}{1+i}[/tex]

If you approach it through a spiral or a parabola then the answer will be something different.

However, for the limit to exist, it wouldn't have to matter how you approach it. Every approach should yield the same answer. This doesn't happen in this case, so the limit does not exist!
 
  • #3
Ah of course! Perfect thank you :)
 

1. Why can't this limit be calculated?

A limit cannot be calculated if there is a discontinuity or a problem with the function at the point where the limit is being evaluated. In other words, the function may have a "hole" or a jump at that point, making it impossible to find a definite value for the limit.

2. How do I know if a limit exists or not?

A limit exists if the values of the function approach a certain number as the input values get closer and closer to a specific value. If the values do not approach a specific number, or if they approach different numbers from different directions, then the limit does not exist.

3. Can I use L'Hospital's rule to solve this limit?

L'Hospital's rule can only be applied if the limit is in an indeterminate form, such as 0/0 or infinity/infinity. If the limit does not have an indeterminate form, then L'Hospital's rule cannot be used.

4. Is there a way to approximate the value of this limit?

If the limit does not exist, there is no way to approximate its value. However, if the limit approaches a certain value from both sides, then we can use the value of the limit from one side as an approximation.

5. Can I use a graph or a table to determine if a limit exists?

Yes, a graph or a table can be useful tools in determining if a limit exists. If the graph has a "hole" or a jump at the point where the limit is being evaluated, then the limit does not exist. If the values in the table approach different numbers from different directions, then the limit also does not exist.

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