d2jsp
Log InRegister
d2jsp Forums > Off-Topic > General Chat > Homework Help > Does .999999... = 1? > Iso Proofs
Prev13637383940121Next
Closed New Topic New Poll
Member
Posts: 27,078
Joined: Jun 20 2006
Gold: 700.00
May 6 2010 10:44am
Quote (AiNedeSpelCzech @ May 6 2010 11:41am)
A number has to terminate before you can round it.

Let x be 0.999...
10x=9.999...
10x-x=9.999... - 0.999...
9x=9
x=1

Unless you can somehow poke a hole in that, you're wrong.


refer to page 2 of this thread and see who posted that first

edit : +16

This post was edited by Taxidermy on May 6 2010 10:44am
Banned
Posts: 422
Joined: Apr 22 2010
Gold: 0.00
Warn: 20%
May 6 2010 10:55am
Quote (AiNedeSpelCzech @ May 6 2010 08:55am)
That....  that is not a thing.  You can't say "An infinite number of digits, followed by a 1." 

And this thread is actually 100% correct.  .999... = 1

It amazes me how many people have difficulty grasping this.


It's pretty amazing that you're most likely clueless with regards to the mathematical proof but are still willing to accept it as fact.
Quote (AiNedeSpelCzech @ May 6 2010 09:41am)
A number has to terminate before you can round it. 

Let x be 0.999...
10x=9.999...
10x-x=9.999... - 0.999...
9x=9
x=1

Unless you can somehow poke a hole in that, you're wrong.




http://forums.d2jsp.org/topic.php?t=41961785&p=287020420

This post was edited by Phils_Porsche on May 6 2010 10:57am
Member
Posts: 112,095
Joined: Jul 25 2008
Gold: 40.42
May 6 2010 11:01am
Quote (Phils_Porsche @ 6 May 2010 11:55)
It's pretty amazing that you're most likely clueless with regards to the mathematical proof but are still willing to accept it as fact.

http://forums.d2jsp.org/topic.php?t=41961785&p=287020420


That's different math you just linked, that assumes x=1. That one's a bit backward.

I'm not really up on my higher maths, but what I posted is pretty much basic algebra and makes no such assumptions. A number multiplied by ten means you smack the decimal over to the right one spot. Pretty simple stuff.
Banned
Posts: 422
Joined: Apr 22 2010
Gold: 0.00
Warn: 20%
May 6 2010 11:06am
bgfbgf

This post was edited by Phils_Porsche on May 6 2010 11:09am
Member
Posts: 27,078
Joined: Jun 20 2006
Gold: 700.00
May 6 2010 11:10am
zzz using logic is obviously retarded





(feel free to quote that one)

edit : +17

This post was edited by Taxidermy on May 6 2010 11:10am
Member
Posts: 112,095
Joined: Jul 25 2008
Gold: 40.42
May 6 2010 02:54pm
Quote (Phils_Porsche @ 6 May 2010 12:06)
bgfbgf


huh

I hadn't thought of it this way and may have to revise my worldview based on this information.
Banned
Posts: 422
Joined: Apr 22 2010
Gold: 0.00
Warn: 20%
May 6 2010 03:00pm
Quote (AiNedeSpelCzech @ May 6 2010 01:54pm)
huh

I hadn't thought of it this way and may have to revise my worldview based on this information.


Let x be 0.999...
10x=9.999...
10x-x=9.999... - 0.999...
9x=9
x=1

9x -x = 8x = 9- .999999..... = 8.0000.....001 = 8( .999999....)

Is that what you're also going to tell me? You're trying to prove .999.... = 1, you can't assume it from the very beginning.

That "proof" isn't rigorous at all. I thought you were good with this logic stuff?

This post was edited by Phils_Porsche on May 6 2010 03:20pm
Member
Posts: 27,078
Joined: Jun 20 2006
Gold: 700.00
May 6 2010 03:53pm
so you guys think that

9.999.... -0.999 =9.0000.....1
i.e. 9 with some infinitely small leftover part?

pathetic....

edit : +18

This post was edited by Taxidermy on May 6 2010 03:53pm
Member
Posts: 112,095
Joined: Jul 25 2008
Gold: 40.42
May 6 2010 07:11pm
Quote (Phils_Porsche @ 6 May 2010 16:00)
Let x be 0.999...
10x=9.999...
10x-x=9.999... - 0.999...
9x=9
x=1

9x -x = 8x =  9- .999999..... = 8.0000.....001 = 8( .999999....)

Is that what you're also going to tell me? You're trying to prove .999.... = 1, you can't assume it from the very beginning.

That "proof" isn't rigorous at all. I thought you were good with this logic stuff?


As I mentioned earlier - there's no such thing as ... and then a number, as far as I know. Saying "After infinity, put this digit" is utterly meaningless.

I didn't say it was particularly rigorous, I just said it was correct and I had yet to see anyone poke a hole in it. If someone can poke a hole in it, then we can go with something with more rigor.
Member
Posts: 31,702
Joined: Mar 21 2007
Gold: 4.00
May 6 2010 07:16pm
a number that infinitely approaches another, for all intensive purposes is usually called the second number
but technically no it's not :/
Go Back To Homework Help Topic List
Prev13637383940121Next
Closed New Topic New Poll