2 + 2 = 5

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2 + 2 = 5

Postby Immortal_Z » Thu May 08, 2008 2:00 am UTC

it's possible, mathematically. you get to try to prove it. bonus points if you get the reference x)

I'll prove it when everyone gives up
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Re: 2 + 2 = 5

Postby Pero » Thu May 08, 2008 3:27 am UTC

Spoiler:
Equivalence modulo 1?


Edit: Whoops, forgot to spoiler.
Last edited by Pero on Thu May 08, 2008 4:12 am UTC, edited 2 times in total.
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Re: 2 + 2 = 5

Postby Immortal_Z » Thu May 08, 2008 3:46 am UTC

I haven't the slightest what that is x)
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Re: 2 + 2 = 5

Postby markfiend » Thu May 08, 2008 3:28 pm UTC

Spoiler:
Rounding errors?

2.4 + 2.4 = 4.8

Round each term to 1 significant figure:
2 + 2 = 5
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Re: 2 + 2 = 5

Postby thc » Thu May 08, 2008 3:34 pm UTC

"2+2=5 for extremely large values of 2"
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Re: 2 + 2 = 5

Postby antonfire » Thu May 08, 2008 4:57 pm UTC

In before
Spoiler:
division by zero. And square roots.
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Re: 2 + 2 = 5

Postby Robin S » Thu May 08, 2008 5:13 pm UTC

Spoiler:
Lemma: 0 = 1 (proof left to the reader)
As a direct consequence of our lemma, it is obvious that 2 + 2 = 2 + 2 + 0 = 2 + 2 + 1 = 5.
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Re: 2 + 2 = 5

Postby lingomaniac88 » Thu May 08, 2008 6:35 pm UTC

Spoiler:
Proof of Robin S's lemma:

Let x be a non-zero number, and set y=x. Thus:

\begin{eqnarray}
x &=& y \\
x^2 &=& xy \\
x^2-y^2 &=& xy-y^2 \\
(x+y)(x-y) &=& y(x-y) \\
x+y &=& y \\
2y &=& y \\
2 &=& 1 \\
1 &=& 0
\end{eqnarray}
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Re: 2 + 2 = 5

Postby Blatm » Thu May 08, 2008 9:38 pm UTC

Spoiler:
The "+1" is silent.
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Re: 2 + 2 = 5

Postby Felstaff » Thu May 08, 2008 10:34 pm UTC

Spoiler:
two plus two has always been five. We've always been at war with Eastasia
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Re: 2 + 2 = 5

Postby ehntoo » Thu May 08, 2008 10:37 pm UTC

Spoiler:
2+2=5 for very small values of 5. xD
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Re: 2 + 2 = 5

Postby Immortal_Z » Fri May 09, 2008 12:34 am UTC

lingomaniac wins, but not through the method that I had found. mark twain/samuel clements was where this topic came from, in a letter to an inlaw or something. If that helps anyone, feel free
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Re: 2 + 2 = 5

Postby Blatm » Fri May 09, 2008 2:38 am UTC

Immortal_Z wrote:lingomaniac wins, but not through the method that I had found. mark twain/samuel clements was where this topic came from, in a letter to an inlaw or something. If that helps anyone, feel free


Spoiler:
All he did was divide by zero, which you can't do, mathematically. This false proof is a well known trick. See http://forums.xkcd.com/viewtopic.php?f=17&t=8119 for many more, more interesting false proofs.
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Re: 2 + 2 = 5

Postby Immortal_Z » Fri May 09, 2008 3:18 am UTC

though, given that they are variables, why is it not possible to do that? To only divide the group of variables, not what they come out to. Similar to simplifying variable filled fraction problems
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Re: 2 + 2 = 5

Postby phlip » Fri May 09, 2008 3:39 am UTC

Because "ab = ac" doesn't simplify to "b = c". It simplifies to "b = c or a = 0".

So if you know that "a = 0" is true (or even could be true), then you can't deduce "b = c" in general.

0*2 = 0*3, but it doesn't follow that 2 = 3.
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Re: 2 + 2 = 5

Postby Immortal_Z » Fri May 09, 2008 3:48 am UTC

ah. i admit defeat. thanks x)
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Re: 2 + 2 = 5

Postby afarnen » Wed May 14, 2008 4:28 am UTC

Spoiler:
1/3 = 0.333... multiplied by three
3/3 = 0.999... same as
1 = 0.999... minus 0.999...
0.000...1 = 0 divided by 0.000...1
1 = 0 i did it


QED
Last edited by afarnen on Wed May 14, 2008 4:43 am UTC, edited 1 time in total.
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Re: 2 + 2 = 5

Postby Mathmagic » Wed May 14, 2008 4:42 am UTC

afarnen wrote:
Spoiler:
1/3 = 0.333... multiplied by three
3/3 = 0.999... same as
1 = 0.999... minus 0.999...
0.000...1 = 0 divided by 0.000...1
1 = 0 i did it

Please tell me this is a joke.
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Re: 2 + 2 = 5

Postby afarnen » Wed May 14, 2008 4:48 am UTC

mathmagic wrote:
afarnen wrote:
Spoiler:
1/3 = 0.333... multiplied by three
3/3 = 0.999... same as
1 = 0.999... minus 0.999...
0.000...1 = 0 divided by 0.000...1
1 = 0 i did it

Please tell me this is a joke.

NEVER! But yeah, the whole point-nine-repeating equals one thing has been around for a while: http://en.wikipedia.org/wiki/0.999...#Fractions
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Re: 2 + 2 = 5

Postby hermaj » Wed May 14, 2008 5:07 am UTC

A) I think I can safely speak for all of us when I say that we are NOT getting into another 0.999... = 1 thing again. Do not even think about it. Do not even hope.

B) I will also take this opportunity to register my minor disappointment that this thread has nothing to do with Radiohead, unless I can hold the desperate hope that that is the reference for which I will get bonus points. Bonus points will appease me. :P
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Re: 2 + 2 = 5

Postby afarnen » Wed May 14, 2008 5:31 am UTC

hermaj wrote:A) I think I can safely speak for all of us when I say that we are NOT getting into another 0.999... = 1 thing again. Do not even think about it. Do not even hope.

B) I will also take this opportunity to register my minor disappointment that this thread has nothing to do with Radiohead, unless I can hold the desperate hope that that is the reference for which I will get bonus points. Bonus points will appease me. :P


hehe i thought about adding that to my post. two and two always equals fiiiive
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Re: 2 + 2 = 5

Postby Mathmagic » Wed May 14, 2008 3:51 pm UTC

afarnen wrote:
mathmagic wrote:
afarnen wrote:
Spoiler:
1/3 = 0.333... multiplied by three
3/3 = 0.999... same as
1 = 0.999... minus 0.999...
0.000...1 = 0 divided by 0.000...1
1 = 0 i did it

Please tell me this is a joke.

NEVER! But yeah, the whole point-nine-repeating equals one thing has been around for a while: http://en.wikipedia.org/wiki/0.999...#Fractions

Yes, I am quite familiar with the 0.999...= 1 "debate" for a long time. You'd be surprised at how many people think they can shove a '1' onto the end of an infinitely repeating decimal. :roll:
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Re: 2 + 2 = 5

Postby afarnen » Wed May 14, 2008 5:58 pm UTC

mathmagic wrote:
afarnen wrote:
mathmagic wrote:
afarnen wrote:
Spoiler:
1/3 = 0.333... multiplied by three
3/3 = 0.999... same as
1 = 0.999... minus 0.999...
0.000...1 = 0 divided by 0.000...1
1 = 0 i did it

Please tell me this is a joke.

NEVER! But yeah, the whole point-nine-repeating equals one thing has been around for a while: http://en.wikipedia.org/wiki/0.999...#Fractions

Yes, I am quite familiar with the 0.999...= 1 "debate" for a long time. You'd be surprised at how many people think they can shove a '1' onto the end of an infinitely repeating decimal. :roll:

well, was my proof any less real than lingomaniac88's?

lingomaniac88 wrote:
Spoiler:
2y = y
2 = 1
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Re: 2 + 2 = 5

Postby Mathmagic » Wed May 14, 2008 6:21 pm UTC

I think it's a little less egregious an error to have a sly divide-by-zero than to show an infinitely repeating decimal terminate with a 1 at the digit "at infinity". :P

But no, both proofs were erroneous.
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Re: 2 + 2 = 5

Postby phlip » Wed May 14, 2008 7:42 pm UTC

Well, since they're both divisions by zero, they're both about as bad as each other... and afarnen's was funnier.
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Re: 2 + 2 = 5

Postby SlyReaper » Wed May 14, 2008 10:04 pm UTC

Permute:
1 -> 1
2 -> 2
3 -> 3
4 -> 5
5 -> 4

And you're done.

Alternatively, apply Lebadevinski's Inequality to the set of Boromian fields, and expand out by Gregorinov's power series. The answer should pop straight out. (Exercise)
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Re: 2 + 2 = 5

Postby J Spade » Sat May 24, 2008 12:43 am UTC

let's make this up as I go along.

sin(0) = 1
sin(2π) = 1
0 = 2π
0 = 1 :: division by 2π
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Re: 2 + 2 = 5

Postby Dobblesworth » Sat May 24, 2008 12:57 am UTC

Slightly inspired by Portal,

4 + 4 = 10base8
(divide both sides by 2)
2 + 2 = 5
[I don't think it would work like that though. Most likely 2 + 2 = 4base8, but for the purpose of this thread I am disregarding a few laws here and there.]
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Re: 2 + 2 = 5

Postby Sungura » Mon May 26, 2008 11:13 pm UTC

2 + 2 = 5

Spoiler:
Because Big Brother said so!
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Re: 2 + 2 = 5

Postby J Spade » Mon May 26, 2008 11:52 pm UTC

amysrabbitranch wrote:2 + 2 = 5

Spoiler:
Because Big Brother said so!


What do you mean? 2+2 has always been 5. Big Brother simply alerted us to our previous errors, which were utterly wrong.
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Re: 2 + 2 = 5

Postby vqcg » Tue May 27, 2008 12:05 am UTC

J Spade wrote:
amysrabbitranch wrote:2 + 2 = 5

Spoiler:
Because Big Brother said so!


What do you mean? 2+2 has always been 5. Big Brother simply alerted us to our previous errors, which were utterly wrong.

Not AWAYS!
2 and 2 are sometimes 5. Sometimes they are three. Sometimes they are both of them at once.
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Re: 2 + 2 = 5

Postby phlip » Tue May 27, 2008 12:07 am UTC

No, 2+2 has always been 5 and always will be 5. Any memories you may have of it being 3 are false, planted there by the Eurasians (who are our enemies, and always have been).
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Re: 2 + 2 = 5

Postby eddiekizer » Tue May 27, 2008 12:53 am UTC

Felstaff:

We have always been at war with Eurasia.
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Re: 2 + 2 = 5

Postby Sungura » Tue May 27, 2008 12:56 am UTC

vqcg wrote:
J Spade wrote:
amysrabbitranch wrote:2 + 2 = 5

Spoiler:
Because Big Brother said so!


What do you mean? 2+2 has always been 5. Big Brother simply alerted us to our previous errors, which were utterly wrong.

Not AWAYS!
2 and 2 are sometimes 5. Sometimes they are three. Sometimes they are both of them at once.


2 + 2 = 5 on Thursdays, and 3 on Saturdays.
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Re: 2 + 2 = 5

Postby Game_boy » Tue May 27, 2008 8:12 pm UTC

The Reaper wrote:Evolution is a really really really long run-on sentence.
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Re: 2 + 2 = 5

Postby ginnybee » Sat Jun 21, 2008 10:52 pm UTC

In addition, there are 5 lights.
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Re: 2 + 2 = 5

Postby markfiend » Sun Jun 22, 2008 12:09 pm UTC

lingomaniac88 wrote:
Spoiler:
Proof of Robin S's lemma:

Let x be a non-zero number, and set y=x. Thus:

\begin{eqnarray}
x &=& y \\
x^2 &=& xy \\
x^2-y^2 &=& xy-y^2 \\
(x+y)(x-y) &=& y(x-y) \\
x+y &=& y \\
2y &=& y \\
2 &=& 1 \\
1 &=& 0
\end{eqnarray}

I prefer:
Spoiler:
\begin{eqnarray}
x &=& 1 \\
x-1 &=& 0 \\
x^2-1 &=& 0 \\
x^2-1 &=& x-1 \\
(x+1)(x-1) &=& x-1 \\
x+1 &=& 1 \\
x &=& 0 \\
1 &=& 0
\end{eqnarray}
Five tons of flax
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Re: 2 + 2 = 5

Postby Actaeus » Sun Jun 22, 2008 2:14 pm UTC

This is clearly an example of emergent attributes.
Ever heard of the phrase "greater than the sum of its parts"? This is an example.
Strict reductionists, of course, would reject the idea.
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Re: 2 + 2 = 5

Postby DarkLordofSquirrels » Sun Jun 22, 2008 6:39 pm UTC

ginnybee wrote:In addition, there are 5 lights.

Even Picard would have to agree that if 2 +2 = 5, there are five lights.

If we say that the symbol "5" is a variable, then the equation has a solution when 4 = 5.

@markfiend: Yours isn't as fun, because it squares x-1 = 0 and gets x^2-1=0, which as we all know is even sillier than dividing by zero ;)
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Re: 2 + 2 = 5

Postby Token » Mon Jun 23, 2008 12:06 am UTC

DarkLordofSquirrels wrote:@markfiend: Yours isn't as fun, because it squares x-1 = 0 and gets x^2-1=0, which as we all know is even sillier than dividing by zero ;)

No, it doesn't. That just follows from the first line. It makes the exact same division by zero error as every other proof like it.
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