2 + 2 = 5

[Immortal_Z]

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

[Pero]

Spoiler:

Equivalence modulo 1?

Edit: Whoops, forgot to spoiler.

[Immortal_Z]

I haven't the slightest what that is x)

[markfiend]

Spoiler:

Rounding errors?

2.4 + 2.4 = 4.8

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

[thc]

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

[antonfire]

In before

Spoiler:

division by zero. And square roots.

[Robin S]

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.

[lingomaniac88]

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}

[Blatm]

Spoiler:

The "+1" is silent.

[Felstaff]

Spoiler:

two plus two has always been five. We've always been at war with Eastasia

[ehntoo]

Spoiler:

2+2=5 for very small values of 5. xD

[Immortal_Z]

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

[Blatm]

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.

[Immortal_Z]

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

[phlip]

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.

[Immortal_Z]

ah. i admit defeat. thanks x)

[afarnen]

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

[Mathmagic]

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.

[afarnen]

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

[hermaj]

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.

[afarnen]

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.

hehe i thought about adding that to my post. two and two always equals fiiiive

[Mathmagic]

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.

[afarnen]

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.

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

Spoiler:

2y = y
2 = 1

[Mathmagic]

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".

But no, both proofs were erroneous.

[phlip]

Well, since they're both divisions by zero, they're both about as bad as each other... and afarnen's was funnier.

[SlyReaper]

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)

[J Spade]

let's make this up as I go along.

sin(0) = 1
sin(2π) = 1
0 = 2π
0 = 1 :: division by 2π

[Dobblesworth]

Slightly inspired by Portal,

4 + 4 = 10_base8
(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.]

[Sungura]

2 + 2 = 5

Spoiler:

Because Big Brother said so!

[J Spade]

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.

[vqcg]

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.

[phlip]

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).

[eddiekizer]

Felstaff:

We have always been at war with Eurasia.
Minitruth requires you to change your post.

-The Ministry of Truth

[Sungura]

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.

[Game_boy]

2 + 2 = 5

What numerical error?

[ginnybee]

In addition, there are 5 lights.

[markfiend]

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}

[Actaeus]

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.

[DarkLordofSquirrels]

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

[Token]

@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.