Pattern of variables with absolute value exponents

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Homework Help Overview

The discussion revolves around the behavior of functions with absolute value exponents, specifically examining the relationship between terms like ##x^{|2n|}## and ##x^{|2n+1|}## within the interval ##x \in (-1, 1)##. Participants are exploring the implications of these expressions in the context of big O notation.

Discussion Character

  • Conceptual clarification, Mathematical reasoning, Assumption checking

Approaches and Questions Raised

  • Some participants question the necessity of absolute values on the exponents given that ##n## is a natural number. Others are attempting to clarify the definitions and implications of the big O notation in relation to the bounds of the functions involved.

Discussion Status

The discussion is ongoing, with participants providing insights and questioning the definitions and assumptions made in the original post. There are attempts to clarify the relationships between the expressions and the conditions under which they hold, but no consensus has been reached yet.

Contextual Notes

There are indications that some participants feel the original question may not be well defined, and there is a focus on the behavior of the functions as ##x## approaches 0 within the specified interval.

mcastillo356
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Homework Statement
Want to prove that, raised to an absolute value, monomials behave bounded
Relevant Equations
Variables raised to natural numbers in absolute value (for my purpose, I do not consider 0 as belonging to naturals)
On ##x\in{(-1,1)}##, ##x\in{\mathbb{R}}##, ##\forall{n\in{\mathbb{N}}}##, ##x^{|2n|}=O(x^{|2n+1|})##
geogebra-export (1).png

Sugestions? Any answer is wellcome!
Greetings, PF
 
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I don't think the question is well defined as written.

Are you looking for something like ##x^n## is bounded in (-1,1)?
 
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Since n is a natural number (##n \in \mathbb N##), what is the purpose of absolute values on the exponents? The natural numbers are integers (no fractional part) that are greater than zero, although one definition also includes zero.
With this in mind, ##x^{|2n|} = x^{2n}##, and similarly for ##x^{|2n + 1|}##.
 
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Office_Shredder said:
I don't think the question is well defined as written.

Are you looking for something like ##x^n## is bounded in (-1,1)?
Yes!
(i) ##x^2\leq{x^{2+n}}##, ##\forall{n\in{\mathbb{N}}}##
(ii) We write ##f(x)=O(u(x))## as ##x\rightarrow{a}## provided that $$|f(x)|\leq{k|u(x)|}$$ holds for some constant ##k## on some open interval containing ##x=a##
(iii) ##|x^2|\leq{k|x^{2+n}|}##, for ##k=1##
(iv) ##x^2=O(x^{2+n})##

🤔
 
##x^2\leq{x^{2+n}}## ?? On ##x\in{(-1,1)}## ??
Am I misssing something essential ?

##\ ##
 
BvU said:
##x^2\leq{x^{2+n}}## ?? On ##x\in{(-1,1)}## ??
Am I misssing something essential ?

##\ ##
Thanks indeed
 
@BvU, it is ##x^{2+n}\leq{x^2}## on ##x\in{(-1,1)}##, ##\forall{n\in{\mathbb{N}}}##

Consequently, #4 must be quoted again, arranged:
mcastillo356 said:
(i) ##x^2\leq{x^{2+n}}##, ##\forall{n\in{\mathbb{N}}}##
(ii) We write ##f(x)=O(u(x))## as ##x\rightarrow{a}## provided that $$|f(x)|\leq{k|u(x)|}$$ holds for some constant ##k## on some open interval containing ##x=a##, (##x=0## in this case)
(iii) ##|x^{2+n}|\leq{k|x^2|}##, for some constant ##k##
(iv) ##x^{2+n}=O(x^2)##, e.g. there is a bound: ##x^2##, ##\forall{n\in{\mathbb{N}}},\; x\in{(-1,1)},\; x\rightarrow{0}##
Right? Greetings, PF. Please, check the LaTeX
 
Last edited:

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