Pattern of variables with absolute value exponents

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SUMMARY

The discussion centers on the mathematical expression ##x^{|2n|}=O(x^{|2n+1|})## for ##x\in{(-1,1)}## and ##n\in{\mathbb{N}}##. Participants clarify that the absolute values on the exponents are unnecessary since ##|2n|=2n## for natural numbers. The conclusion drawn is that ##x^{2+n}=O(x^2)##, establishing a bound for the function as ##x\rightarrow{0}## within the specified interval. The final consensus emphasizes that ##x^2\leq{x^{2+n}}## holds true for all natural numbers ##n## in the interval ##(-1,1)##.

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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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