URGEN taking the power of complex exponential

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Homework Help Overview

The discussion revolves around the properties of complex exponentials, specifically the expression e^(i*2pi*1/15) and its relationship to the expression (e^(i*2pi))^(1/15). Participants are questioning the validity of applying the exponentiation rule (A^(b))^c = A^(bc) in the context of complex numbers.

Discussion Character

  • Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants are exploring why the exponentiation rule does not hold for complex exponentials as it does for real numbers. There are inquiries about the conditions under which the rule is valid and the implications of using complex numbers in exponentiation.

Discussion Status

The discussion is ongoing, with participants providing insights into the limitations of exponentiation rules for complex numbers. Some guidance has been offered regarding the safety of using integer powers, but there is still uncertainty about the general case.

Contextual Notes

Participants note that the application of exponentiation rules may differ based on the nature of the base and the exponents involved, particularly when dealing with complex numbers.

kougou
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Homework Statement



e^(i*2pi*1/15) is equal to ( e^(i*2pi) )^(1/15) = (1)^(1/15)=1

Why this is false?

Homework Equations



((A)^(b))^c=A^(b*c)=A^(bc). Why this isn't the case for complex exponential?

The Attempt at a Solution

 
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kougou said:

Homework Statement



e^(i*2pi*1/15) is equal to ( e^(i*2pi) )^(1/15) = (1)^(1/15)=1

Why this is false?

Homework Equations



((A)^(b))^c=A^(b*c)=A^(bc). Why this isn't the case for complex exponential?

The Attempt at a Solution


Because it isn't. The rule (A^b)^c=A^(bc) doesn't hold for complex exponents. As your example shows.
 
Dick said:
Because it isn't. The rule (A^b)^c=A^(bc) doesn't hold for complex exponents. As your example shows.

But why?
When I use take the positive integer power of complex exponential, it works. What's the rule?
 
kougou said:
But why?
When I use take the positive integer power of complex exponential, it works. What's the rule?

If b and c are integers you should be safe. If A is a positive real and one of b or c is an integer, that should also be ok. Otherwise, I think it's dangerous.
 

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