Pattern of variables with absolute value exponents

AI Thread Summary
The discussion revolves around the expression ##x^{|2n|}=O(x^{|2n+1|})## for ##x\in{(-1,1)}## and the implications of using absolute value exponents. Participants question the necessity of absolute values since natural numbers are inherently non-negative. The conversation clarifies that for ##x\in{(-1,1)}##, the relationship ##x^{2+n}\leq{x^2}## holds true, leading to the conclusion that ##x^{2+n}=O(x^2)## as ##x\rightarrow{0}##. The importance of defining the bounds and conditions for the function's behavior is emphasized throughout the thread. Overall, the discussion seeks to clarify the mathematical relationships and definitions involved in the original expression.
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
 
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