Prove: (z̄ )^k=(z̄ ^k) for z≠0 when k is negative

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Homework Help Overview

The discussion revolves around proving the equality \((\bar{z})^k = (\bar{z^k})\) for complex numbers, specifically when \(z \neq 0\) and \(k\) is negative. The context involves complex conjugation and properties of exponents in complex numbers.

Discussion Character

  • Conceptual clarification, Mathematical reasoning

Approaches and Questions Raised

  • Participants explore the implications of complex conjugation and its effect on powers of complex numbers. There is an attempt to express the complex number in polar form and to clarify the notation used in the original statement.

Discussion Status

Participants are actively questioning the clarity of the original problem statement and are discussing the correct interpretation of the notation. Some have provided guidance on expressing complex numbers in polar form and the effect of conjugation on the exponent.

Contextual Notes

There is uncertainty regarding the notation used for complex conjugation, with participants seeking clarification on whether the original statement was correctly interpreted. The discussion also touches on the implications of negative exponents in the context of complex numbers.

shannon
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Homework Statement


Prove that (z̄ )^k =(z̄ ^k) for every integer k (provided z≠0 when k is negative)


Homework Equations





The Attempt at a Solution


I let z=a+bi so, z̄ =a-bi
Then I plugged that into one side of the equation to get
(a-bi)^k
I was going to try to manipulate this to get [(a-bi)^k]
But I don't know where to go from here, or even what to do...
Please HELP!
 
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shannon said:

Homework Statement


Prove that (z̄ )^k =(z̄ ^k) for every integer k (provided z≠0 when k is negative)
This is a bit unclear. From the rest of your post, it looks as if by ̄ you meant the complex conjugation. So did you mean to write

[tex](z^*)^k = (z^{* k})[/tex] ??

But even this is unclear since most people would interpret the two sides to mean the same thing.

It would make more sense if the question was to prove

[tex](z^*)^k = (z^k)^*[/tex]

was that the question?


If so, then write the complex number z in polar form [itex]r e ^{i \theta}[/itex]
 
Is the bar over the z only in both parts? Or is it

[tex]\bar{z}^{k} = \bar{\left(z^k\right)}[/tex]
 
nrqed said:
This is a bit unclear. From the rest of your post, it looks as if by ̄ you meant the complex conjugation. So did you mean to write

[tex](z^*)^k = (z^{* k})[/tex] ??

But even this is unclear since most people would interpret the two sides to mean the same thing.

It would make more sense if the question was to prove

[tex](z^*)^k = (z^k)^*[/tex]

was that the question?


If so, then write the complex number z in polar form [itex]r e ^{i \theta}[/itex]


Yes, that is my question. Sorry for the lack of clarity.
So I rewrote z in polar form, but I wasn't sure about what the conjugate of that would be...would the exponent just be negated? (the iѲ term).
If that was the case, would I simply combine the exponents in the left side of the equation, multiplying the k and the iѲ term thus resulting in the right side of the equation?
I hope I'm being more clear!
 
shannon said:
Yes, that is my question. Sorry for the lack of clarity.
No problem!
So I rewrote z in polar form, but I wasn't sure about what the conjugate of that would be...would the exponent just be negated? (the iѲ term).
Yes. Complex conjugation just means that we replace any "i" we see by -i. So yes, the sign of the exponent changes.
If that was the case, would I simply combine the exponents in the left side of the equation, multiplying the k and the iѲ term thus resulting in the right side of the equation?
I hope I'm being more clear!
Exactly! Basically, k times (i)* gives the same thing as (k times i)*
 

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