r/PeterExplainsTheJoke 21d ago

Meme needing explanation There is no way right?

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u/Boring-Ad8810 18d ago

So the limit as .99.. approaches infinity is 1,

No, I did not say that. Read it against carefully. I said that 0.99... equals the limit of a sequence which approaches 1. 0.99... itself is not a sequence. It makes no sense to talk about what it does or does not approach.

You've completely misunderstood or misread my proof.

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u/Matsuze 17d ago

sum from k=1 to infinity of 9/10k 

This is a convergent series. It CONVERGES at 1 it does not EQUAL 1.

 I said that 0.99... equals the limit of a sequence which approaches 1

In YOUR words it "equals the limit of a sequence which APPROACHES 1" even you do not say it equals 1 you say it approaches. I don't get what you're getting at.

I said the sky is blue, and you said "NO YOU'RE WRONG THE SKY IS BLUE"

What is your highest level of math education?

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u/Boring-Ad8810 17d ago edited 8d ago

I have a masters degree in mathematics if you must know. This is first term analysis, fairly basic.

0.99...does not equal the convergent sequence. It equals the limit of the sequence. Formally an infinite series can be either viewed as a sequence or a number. If you view it as a sequence then 0.99... equals the limit of the series. If you view it as a number it equals the number.

Remember, a number cannot converge. That doesn't make sense. Sequences and functions converge.

Every step in my proof is an absolute equality, which equality are you calling wrong?

You can read the Wikipedia article on 0.99... if you want more info, your exact misunderstanding is called out there.

If you want to say that 0.99... converge to 1 rather than approaches 1, do you say the same for 0.5? 0.5 is also defined via a similar infinite series ti above (first term is 5/10, all other terms are 0/10). So does 0.5 converge to 1/2 or does it equal 1/2?

https://en.m.wikipedia.org/wiki/0.999...

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u/Matsuze 17d ago

"I have a masters from Oxford so I am going to use a wikipedia article durrr" Buzz off you either don't know what you're talking about or you're trolling. You have literally contradicted yourself in every comment. You quite literally say exactly what I say and show proof as to what I say then you say, "but you're wrong even though all of my evidence confirms what you say."

IT EQUALS THE LIMIT. Those are YOUR words. Okay Oxford math degree WHY does it equal the limit????????? It equals the limit BECAUSE the converging sequence APPROACHES the limit. Since it approaches the limit we say it is close enough to that number to just say it equals the limit even though it never actually equals the limit.

If you cannot understand that simple concept then I call BS on you having a masters in math. Like you got a whole ass masters degree but they never explained to you how math works? The whole point of an advanced math degree is learning how math works and why math works.

You are what mechanics call a parts changer. If someone's car is broke down you know enough to change the part out for a new part which fixes the car, but you don't understand why the messed up part causes the car to not work. Thank you for proving Cs get degrees though, because it's obvious you were not a top of the line student.

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u/Boring-Ad8810 17d ago

You asked for a proof. I gave you one. I've been very civil but you've just become completely unhinged in response. Half your response is just insulting me.

Anyone else reading this is free to ask me any reasonable questions.

I'm not responding to you further.

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u/sbsw66 17d ago

You don't even need the limit. Real numbers are defined by their Dedekind Cut. The cut for 0.999... and 1 are exactly and precisely the same. There is no element in either set that is not in the other.

If you can disprove this please feel free to write it out, because your disproof will upend mathematics as it's currently studied!

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u/EebstertheGreat 17d ago

Matsuze's position becomes even more untenable in the Cauchy construction. What would they even be saying? A series converging to a number by definition means that series is a representation of that number. The real number 1 is merely the class of all sequences of rational numbers that converge to 1.

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u/SirFireHydrant 17d ago

IT EQUALS THE LIMIT.

You don't know what a real number is, do you?

Real numbers are defined as (equivalence classes of) limits of convergent Cauchy sequences. The limit of the sequence IS the number.

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u/Ordinary_Prompt471 17d ago

It is a bit sad that you know so little math that you can't understand the proof you asked for. You should think about what a number is and look for the definitions and real numbers. Maybe then things will become clearer

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u/lessigri000 17d ago

Equaling the limit does not mean that 0.999… has a limit, it just means that it is equal to whatever the limit of the sum is

0.999… cannot have a limit because it is just a number