Is x^pi Real for Negative Values of x?

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Discussion Overview

The discussion centers on the nature of the function x^π for negative values of x, exploring whether it yields real or complex results. Participants examine the implications of the function's behavior and its classification as odd or even, while also considering the definitions and properties of odd numbers in relation to π.

Discussion Character

  • Debate/contested
  • Mathematical reasoning

Main Points Raised

  • One participant notes that the plot of x^π appears odd, questioning whether this implies that π is an odd number.
  • Another participant asserts that the functions x^π and x^e are real only for x ≥ 0, and clarifies that this does not make π an odd number.
  • A further contribution defines an odd number as one that can be expressed in the form n = 2k + 1 for some integer k, suggesting this definition should be applied to π.
  • One participant reiterates the claim about the functions being real only for non-negative x and questions the reasoning behind this assertion.
  • A later reply explains that for negative x, the expression (-x)^π can be decomposed into (-1)^π * x^π, indicating that the (-1)^π factor is complex, thus leading to a complex result unless certain conditions are met.
  • This participant also mentions that the analysis can be generalized to any power x^α, but cautions that the situation becomes more complex with rational values.

Areas of Agreement / Disagreement

Participants do not reach consensus on whether x^π is real for negative values of x, with multiple competing views presented regarding the nature of the function and the implications of π being classified as odd.

Contextual Notes

The discussion involves assumptions about the behavior of functions for negative inputs and the definitions of odd numbers, which may not be universally accepted or fully resolved within the conversation.

cstvlr
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The plot of x^(pi) looks like an odd function, does that make pi an odd number?

http://www.wolframalpha.com/input/?i=x^pi

same goes for x^e

http://www.wolframalpha.com/input/?i=x^e
 
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Those functions are real for x\geq 0 only. If you take a look at that interval for both odd and even functions, you'll realize that you can't really tell a difference between their shape.
And no it doesn't make pi an odd number.
 
the definition of an odd number n is a number that's able to be expressed as n=2k+1 for some integer k. use that definition to see if pi is an odd number.
 
Mentallic said:
Those functions are real for x\geq 0 only. If you take a look at that interval for both odd and even functions, you'll realize that you can't really tell a difference between their shape.
And no it doesn't make pi an odd number.
why is that true?
 
mxbob468 said:
why is that true?

Because if we take some positive number x, then (-x)^{\pi}=(-1)^{\pi}\cdot x^{\pi}
Since x is positive, x^{\pi}>0 so we just have to deal with the (-1)^{\pi} factor. It is complex, but if you want a proof of this, simply convert it into its complex form:

e^{i\pi}=-1 therefore (-1)^{\pi}=e^{i\pi ^2}=cos(\pi ^2)+isin(\pi ^2) so if it is to be a real number, then the sin of \pi ^2 needs to be equal to 0, but this isn't the case.

In fact we can take any power x^{\alpha}, and deduce the circumstances whether it will be real or complex for negative values of x by following a similar process. But be wary, it is a little more complicated dealing with all rational values.
 

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