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/sci/ - Science & Math


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5984756 No.5984756[DELETED]  [Reply] [Original]

Hey /sci/, why do mathematicians believe that 0.999... = 1 ?

Even a 6th grader could disprove it.
Allow me to demonstrate.
1 - 0.000...1 = 0.999... = 1
However, 0.999... - 0.000...1 = 0.999...8, which decisively != 1. How do mathematicians make this mistake all the time, and then claim that they're great at math?!

>pic related, it's mathematicians' response when anyone dares challenge their narrow-minded (AND WRONG) views of math

>> No.5984761

Also, not trolling, genuinely curious as to how people who are self-proclaimed masters in their field can ignore such an obvious logical conclusion

>> No.5984768

You can't have a number after an infinite string of numbers, if it never ends where would you find the 8

>> No.5984769

>>5984756

.000....1? As in, an infinite number of zeros,and then AFTER that INFINITE number of zeros, a 1? Do you see how that number could not exist?

>> No.5984785

>>5984769
It's just a notation. Like 0.999... Or do you think a number with infinite 9s can LITERALLY exist?

>> No.5984788

>>5984785

See, but .999.... doesn't defy definitions. It's expressible mathematically, and is consistent with mathematical definitions.

.000.....1 is not. There is a class of numbers where in they can be invoked (Read: Hyperreal numbers), but it's not the standard real numbers.

>> No.5984792

>>5984788
0.000...01 can be rigorously defined as the limit of (1/10)^n as n goes to infinity. Consistent and logical.

>> No.5984793

>>5984792

That limit is 0.

>> No.5984797

>>5984793
If 0.999.. is a notation for 1, then 0.00...01 is a notation for 0.

>> No.5984798

Here ya go dum dum

http://www.youtube.com/watch?v=TINfzxSnnIE

>> No.5984799

>>5984756
doesn't even know whats happening in the pic just ignore the troll

>> No.5984805

>>5984797

Well, .000...1 being 0 is a non-sensical representation for that number, but if that's the case, then

1-.000...1=.999....

Is equivalent to

1=.999....

So you agree that they are the same number.

>> No.5984808

>>5984798
http://www.youtube.com/watch?v=wsOXvQn3JuE

>> No.5984820

>>5984756
>0.000...1

At best you're defining a finite number of digits, which isn't he same thing as 0.999...

>> No.5984824

>>5984805
#rekt

>> No.5984825

>1 - 0.000...1 = 0.999... = 1
First step is wrong. Any conclusions therefore are not correct
If you do 1-0.999999, what is the last digit? You assume it is 1, but the last digit is 0 (ie. there is no last digit).

>> No.5984834

>>5984768
at the end

>> No.5984917
File: 34 KB, 413x395, draper.jpg [View same] [iqdb] [saucenao] [google]
5984917

>>5984792
<span class="math">0.999...=\lim_{n\to\infty}1-\frac{1}{10^n}=1[/spoiler]

>> No.5984923

>>5984792
>>5984917
By the way, the scoffing Draper was meant for everybody else

>> No.5985700

>>5984917

Neat.

>> No.5985708

.000...1 is not a number. You can't have something following an infinite amount of something else otherwise you wouldn't have an infinite amount of zeros anymore, get it?

>> No.5985749

>1/3 = 0.333333333.........

>1/3 + 1/3 = 0.33333.... + 0.333333..... = 0.66666..... = 2/3

>2/3 + 1/3 = 0.666666.... + 0.3333333..... = 0.9999999..... = 3/3 = 1

Therefore, 0.9999999999........ = 1

>> No.5985778

>>5985749

Let me just save us all a head ache that we all know is coming.

What this person has done does not constitute a rigorous proof. It is a great way to show that there's some logical reasons to believe that the seemingly impossible statement 1=.999.... statement is true.

Rigorous proofs do exist (Of particular note, the formula for evaluating an infinite geometric series).

>> No.5985788

>>5984768
There could be an infinite amount of numbers between the end number and the start one dingus.

>> No.5985795

>>5985788

No, there can't be, because then your "end number" would be AFTER an infinite number of digits.

Infinite means without termination, after means once termination has happened, they literally contradict each other if you use them simultaneously.

>> No.5985804

>>5984785
Dude, you are a moron.
... implies infinity. You can't have infinity and then something after that.

>> No.5985805

>>5985788
This is where you are wrong.

>> No.5985812

>>5985788
The property of having an "end" is intrinsic of termination, which is intrinsic to finite numbers. For any infinite number, there is no termination, thus no end can be found.

1/3 = 0.333...
0.333...*3 = 0.999...
1/3*3 = 1
Thus 0.999... = 1
QED.

>> No.5985813

>>5984756
Yes, it seems illogical for 0.999... to equal one, but first we have to look at how we define are number system. One of the ways we define two different numbers is if there is a number between them. Now here's the kicker, there is nothing between 0.999... and 1. So, logically, yes, 1 does not equal 0.999.... However, with the way that set of numbers is defined, they are the same thing.

>> No.5985815

>>5985813
Mathematics is the very foundation of logic. When you say "logic", you really mean your own troglodyte senses.

>> No.5985816

>>5985795

Not the person you're responding to. You clearly do not understand what math is, and what math is not.

>> No.5985818
File: 26 KB, 300x369, Omega-exp-omega-labeled.svg.png [View same] [iqdb] [saucenao] [google]
5985818

>>5985708
>You can't have something following an infinite amount of something else
Sure you can — this is true of every infinite ordinal number except ω, which is the order type of the natural numbers. But by definition, a sequence has order type ω, so that's the reason why there can't be any digits occurring at infinite index.

Pic related: the ordinal <span class="math">\omega^\omega[/spoiler].

>> No.5985820

>>5985816

Care to enlighten me then?

>> No.5985822

>>5985812

You're making assumptions about reality and thus math. Math is conceptual and plays by man-invented rules that mimic reality. But when you can only make assumptions about reality (Especially with Occam's razor of all things, lol), math becomes metaphorical again. Which is what it should be.

>> No.5985821

>>5985815
No, I mean that by calling an orange an apple, you are wrong. To someone that knew what the world "equals" means, but didn't know our number system, if you were to ask them DOES 0.999... EQUAL 1. If they had any intelligence whatsoever, they would say no. However, although I agree with you that math is the very foundation of logic, the way that that particular set is defined, doesn't really fit. It's an inconsistency. Not an illogical one, but an inconsistency nonetheless.

>> No.5985824

>>5985821
Now you're confusing different symbols representing the same values with different values. This is a common error among the low IQ.

No one in this thread, or anywhere in the mathematical community, have ever claimed that the symbols of 0.999... and 1 lack differentiation. For one, they have a tremendous difference in number of strokes. But this is not the issue, the issue is value, which is the only thing the equals sign deals with.

What you're saying is as moronic as if someone would exclaim that 2/2 does not equal 1 simply because the symbols are different, when they are as mathematically identical as 0.999... and 1.

>> No.5985830
File: 46 KB, 304x304, billy-joel.jpg [View same] [iqdb] [saucenao] [google]
5985830

>>5985820
>0 replies
just responding to let you know that you won the argument

congrats

>> No.5985834

>>5985824
Except 2/2, using defined processes, can be turned into 1. .999... can not turn into 1 through an equation or process. It is simply that since there is no other number between them, they are the same number, because that is how the set is defined. Why are you attacking me personally with quotes such as "This is a common error among the low IQ.", using a strawman arguement, and even then not fully understanding what I was saying.

Why don't you read the 'proofs from the construction of the real numbers' paragraph in http://en.wikipedia.org/wiki/0.999......

>> No.5985862

>>5984756
>0.00...1
>logic

>> No.5986073

>>5984798
So at the very end we still can't have a nice set, but only an ugly proper class. Bagh

>> No.5986078

>>5985834
But actually it can
1/3 = 0.333...
1/3*3 = 0.333...*3 = 3/3 = 0.999... = 3/3 = 1

>> No.5986116

Is 0.9 equal to 1? No.
Is 0.99 equal to 1? No.
Is 0.999999 equal to 1? No.
Is 0.999... equal to 1? No.

>> No.5986163

If we assume that 0.999... = x

0.999... = x

We times by 10

9.999 = 10x

We subtract 1x

9 = 9x

Divide by 9

9 / 9 = 9x / 9
1 = x

>> No.5986215

>>5985812
but 1/3 =/= 0.333...
because 0.333...*3 = 0.999... =/= 1

>> No.5986217

>>5986215
And that's, kids, how you properly use circular logic.

>> No.5986220

>>5986215
Looks at >>5986163

>> No.5986238

>>5985778
I know the rigorous proof you're talking about, it's the one I use whenever I need a proof of that equality, but which part of that guy's proof isn't rigorous ?
Is is the <span class="math">\frac{1}{3} = 0.\bar{3}[/spoiler] part ?

>> No.5986244

>>5986215
okay.... theople here seem to be forgetting that 0.999... is an infinatly long number, meaning that there is no number between 0.999... and 1 and no possible number that can get you from 0.999... to 1. and secondly 1/3 is 0.333... and 0.333x3 is 0.999... now without changing any number in the sum you get a different answer than the one you started with. mathimatically this would not happen if anything we use to calculate number could calculate to an infinate number, but as we are limited too an actuall number, we end up with 0.999... instead of 1, so only whilst using thirds does 0.999...=1

>> No.5987321

Pi is infinite, too, and it doesn't suddenly become a different number.

>> No.5987351 [DELETED] 

>>5984756
Why is it so hard for some people to understand that if you have an infinite amount of 9's and answer in a troll thread, then you are bound to get trolled even harder.

>> No.5987366

>>5984756
fuck off OP people smarter than you have proven this

>> No.5987382

>>5986116
0.9 + 0.1 = 1
0.99 + 0.01 = 1
0.999999 + 0.000001 = 1

so what number do you add to 0.999... to make it equal one? remember 0.000...1 isn't a number in the proper sense.

>> No.5987393

For fucks sake, /sci/ couldn't spot a troll if it sat on them.

>> No.5987416

>>5984808
haha its an april fools joke

>> No.5987437
File: 106 KB, 953x613, 0.999=1.jpg [View same] [iqdb] [saucenao] [google]
5987437

>>5984756
>Infinitly small number don't exist
/thread

>> No.5987449

>>5984756
>why do mathematicians believe that 0.999... = 1

They don't believe that. Clearly they are 2 completely different decimal strings and as such they CAN NOT logically be equal (and no, every single arithmetic 'proof' is only a disproof of decimals forming a field, not equality).

What mathematicians know and can prove is that if you DEFINE an equivalence relations on the set of all infinite decimals that puts all finite nonzero decimals in correspondence with one were the last digit is decremented and an infinite trail of 9s are appended; then that forms the real number system under the usual definition of 0,1,+,*,< on these equivalent classes.

It's by definition. Anyone who says you can prove it is a fool, including your high school math teachers.

>> No.5987463

>>5987449
Uh, wow. I don't think I've ever seen someone try to argue mathematics on the basis of STRING COMPARISONS before. Normally it's taken as given that we're talking about numerical comparisons, within the existing definitions of that number set.

>> No.5987475

>>5987463
>I don't think I've ever seen someone try to argue mathematics on the basis of STRING COMPARISONS before

Take a Mathematical Logic course or read a book on it. (A real one, not some hand waving Philosophy or CS crap)

>Normally it's taken as given that we're talking about numerical comparisons, within the existing definitions of that number set.

You can't say anything numerically until you well define the underlining set and operations on it.

>> No.5987493

>>5987475
>You can't say anything numerically until you well define the underlining set and operations on it.
Sure, but you don't do that every time you try to buy groceries. You do that once in a Uni course, and then assume it for the rest of your life.

>> No.5987504

>>5984769
It is as likely to exist, as an infinite number is likely to exist. Mathematicians work with theoretical numbers all the time, this is a relatively simple one in comparison.

>> No.5987514

>>5987504
That's not how numbers work.
Good day.

>> No.5987990
File: 100 KB, 480x480, 1375271333810.png [View same] [iqdb] [saucenao] [google]
5987990

>>5985818
>tfw the supremum of the sequence
<span class="math"> \omega [/spoiler]
<span class="math"> \omega^{\omega} [/spoiler]
<span class="math"> \omega^{\omega^{\omega}} [/spoiler]
is countable