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.9999... = 1?

_Keno_

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why don't you think .33repeating is rational? Which decimal numbers do you think are rational?
pretty much all non-repeating decimals. I say this because I do not agree that they are EXACTLY the same (.999 repeating and 1; .333 repeating and 1/3). Lets just say that if they were lines/curves then .333repeating approaches but never touches 1/3. Once again, I say that they might as well be the same, but aren't. The fact that it isn't exactly the same is pretty much negligible.
 

Elemennop

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pretty much all non-repeating decimals. I say this because I do not agree that they are EXACTLY the same (.999 repeating and 1; .333 repeating and 1/3). Lets just say that if they were lines/curves then .333repeating approaches but never touches 1/3. Once again, I say that they might as well be the same, but aren't. The fact that it isn't exactly the same is pretty much negligible.
but 1/3 = 0.1 in base 3, which is non repeating. Or, 1/2 = 0.111repeating in base 3 (but 0.5 in base 10). Seems like whether a number is rational or not shouldn't depend on what base you're working in.
 

_Keno_

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but 1/3 = 0.1 in base 3, which is non repeating. Or, 1/2 = 0.111repeating in base 3 (but 0.5 in base 10). Seems like whether a number is rational or not shouldn't depend on what base you're working in.
I'm saying that 1/3 is rational and .333repeating is not.

well, 1/3 is a rational number, but I do not agree that .333 repeating is.
 

GTR!

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I have nooooo clue about a lot of the **** that is said in this thread

but i just read the whole 3 pages and my mind is blown.

Seriously. Holy ****.
 

Elemennop

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So if .333repeating and 1/3 are not the same number, there must be some number that exists between them. What is such a number?

Edit: Or, if you want, you could tell me how far apart these two numbers are. If they are different, there must be some positive distance between them. I'll even be nice and just take a lower bound on the distance between them.
 

Gerbil

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I still think .333... repeating is rational based on how rationals were determined. I had always been under the impression that repeating decimals were categorized as rational, and I've seen a basic proof of why. If I find it again, I'll post it.

This whole thread has been really interesting! : )
 

ph00tbag

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@Cheap Peach

Draw out a long division corner.

Put a three on the left, put a one in the corner.

3 does not go into 1, so put a zero over the one and go to the remainder and add a zero.

3 goes into ten 3 times, so put a decimal, then a three, because you're in the tenths digit by this point.

I won't bore you with the rest of this, because frankly, I'd hit the post limit without actually proving it. Suffice to say, you could carry this on indefinitely, and your result will ever approach 0.333..., thus showing that 1/3 = 0.333.... There is absolutely no other way to represent the number in decimal form. For all intents and purposes, 0.333... is a rational number.
 

MarsFool!

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everything in this topic is wrong

1/3 as a decimal is nothing more than a concept.

1/3 = .33333
1/3 = .33333
1/3 = .33334

is the only way 1/3 = .3 in which case it can not be .3333 and .3334

You guys are implementing an imaginary .01 at the END of an INFINITE number.

Logic. get SOME.

all fractions = decimals, but not the other way around.
 

MarsFool!

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What your describing is Einsteins theory of relativity, where as you approach the speed of light, time slows, and all time stops in an inertial reference frame that is moving at the speed of light. What he is describing is that scientists proved that such a reference frame exists as something other than light. However if this were proven, all of Einsteins theory of relativity would be faulted. So as of know its a possible theory, with mathematical proofs that have variables in them. I think that is what he was talking about?

Edit: The clocks thing has happened, because they got it up to mach 5 (in that experiment) so the time slowed on the clock inside. They went for a while and the time was different when it got back. Unfortunately, other than the fact that it has to do with Einsteins theory of relativity, and that nothing can go faster than the speed of light, i can't tell you the reason why.
They did make theory of relativity practically false When they discovered that black holes past the event horizon have more mass (and thus gravity) than legitamately possible via einsteins theory. Also time in the event horizon is roughly half of "regular" time thus time isnt really relative but space is.


Double post: Banzors me now please Q_Q
 

blindghost

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everything in this topic is wrong

1/3 as a decimal is nothing more than a concept.

1/3 = .33333
1/3 = .33333
1/3 = .33334

is the only way 1/3 = .3 in which case it can not be .3333 and .3334

You guys are implementing an imaginary .01 at the END of an INFINITE number.

Logic. get SOME.

all fractions = decimals, but not the other way around.
1/3 as a decimal is way more than a concept... Quite simply:

i=1
Σ 3*10^-i


and it is easy to see 3/10+3/100+3/1000+... as decimals and also to show that 1/3=0.333...

We are not wrong. You're wrong to think that we had made the above assumption.

And secondly 1/3 and 0.333... are equivalent and rational. period. that is the definition of a rational number; it comes from the root ratio.

And lastly. 0.333...+0.333...+0.333...=1. See my justification for assuming 0.999...=1 on the previous page.


They did make theory of relativity practically false When they discovered that black holes past the event horizon have more mass (and thus gravity) than legitamately possible via einsteins theory. Also time in the event horizon is roughly half of "regular" time thus time isnt really relative but space is.


Double post: Banzors me now please Q_Q
The theory of relativity is intact. I'm pretty sure Hawking has a lot of information for you on black holes. You seem to have been led astray there. No such discovery is even possible; that or you have misspoken.
 

MarsFool!

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lmao

1 does not divide evenly by 3. Nor did I say it was irrational.

Youre all silly.
http://en.wikipedia.org/wiki/0.999...

^^ They can both represent 1. But equivalent numbers they are not which is why we are having this discussion.


edit for off topic: pm me to talk about space (but the last episode of steven hawkings into the universe is where I got that info from ;D)

:)
 

_Keno_

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(but the last episode of steven hawkings into the universe is where I got that info from ;D)
I have those on my DVR, so good. Also have the morgan freeman's "into the universe" Havent watched it yet though.

As for the main argument...

If .999re is the same as 1, then what is the difference between the max values of

0 < x < 10 and 0 < x < 10

wouldn't the max value for the first be 9.999re and the second be 10, but according to you guys it is the same? What is the difference between the two equations?
I just got out of hs btw, so this is pretty much me learning rather than debating lol
 

Elemennop

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What do you call the max of a set? The largest element in that set? Then the first equation has no max element, because you can always just take the average of that element and 10 to get another element in the set that's bigger than your previous guess.

This is why instead of max, we work with least upper bounds (or supremum). Wiki it. And the least upper bounds of both sets is the same (10, or 9.9999repeating, whichever you prefer).

@marsfool: I don't get why you say they aren't equivalent numbers, when the wiki article you linked basically says just that. Unless by "non-equivalent" you mean just that they are written differently; but then, are .5 and 1/2 not equivalent?
 

MarsFool!

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Gotta read the whole thing, parts in there show reasoning why it isnt the same but is treated like it is. Algebraic proofs have holes in them and this is just one according to that article.

and whoops i meant steven hawkings but i forgot they came on back to back with Morgan freeman :laugh:
 

Ch3s

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They did make theory of relativity practically false When they discovered that black holes past the event horizon have more mass (and thus gravity) than legitamately possible via einsteins theory. Also time in the event horizon is roughly half of "regular" time thus time isnt really relative but space is.


Double post: Banzors me now please Q_Q
The thing is, Einstein proved Newtons theories wrong about gravity, but in order to calculate the strength of it, Newtons gravity equations still work. Now Einstein and modern black hole and string theory are slightly different, but a similar concept exists. Einsteins theory holds for as far into the universe as is relevant to us. The only exception to Einsteins rule that scientists have theorized are the first 200 something atomic seconds after the big bang, during which time the universe was expanding faster than the speed of light. No other place has any sort of (believable/viable/probable/not insane/most importantly provable) theory suggesteingan object surpassing the speed of light. As far as what you are saying, a guy above me said it. We do not know anything beyond the existance of an event horizon. We can't, because we cant see past it, or even see it, and obviously have not visited it. Even black holes have only been observed indirectly (lack of light). This means that wormholes, new dimensions, and areas which break modern laws of physics are all theories made, albeit by brilliant people, but just to entertain ideas as to the importance of finding a way past the event horizon. Also our universe was made, and the laws of physics formed with it (im religious, but don't believe in the genesis creation), so any argument about the beggining of the universe when even the laws were still non existant, and any alternate dimensions or universes are not valid proof that any theory of physics is false, in the universe at least.
 

Elemennop

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Gotta read the whole thing, parts in there show reasoning why it isnt the same but is treated like it is. Algebraic proofs have holes in them and this is just one according to that article.

and whoops i meant steven hawkings but i forgot they came on back to back with Morgan freeman :laugh:
I read through the wiki article, and didn't find anything indicating that these two are not one and the same. You are right in that algebraic proofs are not entirely sufficient, insofar as that if one has trouble understanding .9repeating = 1, they will have some disagreements with the arithmetic involved in those algebraic proofs.

On the other hand, this does not mean that these numbers are not equal. If you truly have qualms with believing this fact, you should, if you can, read on how the real numbers are constructed (it is not simple, even though we have been using them and taking them for granted since grade one). Once you understand how the reals are constructed, it is an immediate consequence, without proof, that .9repeating = 1.
 

Ch3s

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I read through the wiki article, and didn't find anything indicating that these two are not one and the same. You are right in that algebraic proofs are not entirely sufficient, insofar as that if one has trouble understanding .9repeating = 1, they will have some disagreements with the arithmetic involved in those algebraic proofs.

On the other hand, this does not mean that these numbers are not equal. If you truly have qualms with believing this fact, you should, if you can, read on how the real numbers are constructed (it is not simple, even though we have been using them and taking them for granted since grade one). Once you understand how the reals are constructed, it is an immediate consequence, without proof, that .9repeating = 1.
Just out of curiosity, are you speaking of what i mentioned in my first post at the bottom? If not, im curious what you are talking about because i listened to a lecture on real numbers and there derivations and such.
 

Elemennop

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I'm just saying that from the construction of real numbers (using dedekind cuts or equivalence classes of Cauchy sequences), the fact the two numbers are equal (and any terminating decimal having two expansions) is an immediate consequence.
 

ph00tbag

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MarsFool, I think you're misinterpreting that section on Dedekind cuts. The bit at the end there describes an alternate number system where 1/3 has no representation, and 0.999... =/= 1. Feel free to adopt this system if you are really that dead set on your position here, but don't complain to me when you find that multiplication doesn't work right.
 

MarsFool!

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late response
@elemennop: ill recheck it, but I stand by my view. Im pretty sure I have it down pretty well hence my discontent with it.

@ches: I didnt see your post before, but Im going with what steven hawking says. No offense, but he has it down better than all of us so his theory until I can derive otherwise, Is what im going to use.
 

Chis

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So has anyone used the formula for the sum to infinity yet? It should find the fractional equivalent for 0.999...

a=first term
r=common ratio

S=a/1-r

0.999...
0.9+0.09+0.009+...
r=0.09/0.9=0.1
a=0.9

S=0.9/1-0.1
S=0.9/0.9
S=1 is the fractional equivalent for 0.999...
 

ph00tbag

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So has anyone used the formula for the sum to infinity yet? It should find the fractional equivalent for 0.999...

a=first term
r=common ratio

S=a/1-r

0.999...
0.9+0.09+0.009+...
r=0.09/0.9=0.1
a=0.9

S=0.9/1-0.1
S=0.9/0.9
S=1 is the fractional equivalent for 0.999...
I think this one's been mentioned. At the very least, it's given in the Wikipedia entry that MarsFool posted.
 

Gerbil

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I generally don't use infinite sums to determine solutions such as "equal to" because it can be argued that a summation is just a value to which a series converges or diverges to, not an actual solution (hence also why a limit of a function is a said number, but that function will never actually equal that number).

Again, that's just my take. : )
 

blindghost

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I generally don't use infinite sums to determine solutions such as "equal to" because it can be argued that a summation is just a value to which a series converges or diverges to, not an actual solution (hence also why a limit of a function is a said number, but that function will never actually equal that number).

Again, that's just my take. : )
Numbers can be expressed as an infinite sum. There's a way to construct them to do so.
 
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