2 + 2 = 5 (proven)

[Tomkraven]

Hi guys. a couple of months ago me and my physics teacher were checking this odd equation that was completely logical but still imposible. So here its goes:

20 = 20

-20 = -20

16-36 = 25-45

16-36 + 81/4 = 25-45 + 81/4

(4 - 9/2)sq = (5 - 9/2)sq

following the ecuation we can erase the sq( squared) and the 9/2 so:

4=5

2 + 2 =5

Now... whats your opinions about this?

 

[whaahppnd]

I don't see why this belongs in the debate hall. It is simply a mathematical error.

following the ecuation we can erase the sq( squared) and the 9/2 so:

There's your mistake. You can't just "erase the sq" without accounting for the negative sqrt as well. Just because 1^2 and (-1)^2 are equal does not mean 1=-1

 

[Tomkraven]

I don't see why this belongs in the debate hall. It is simply a mathematical error.


There's your mistake. You can't just "erase the sq" without accounting for the negative sqrt as well. Just because 1^2 and (-1)^2 are equal does not mean 1=-1

theres no error in my procedure, what i did with the ecuation was simple algebra:

(A-B)sq = Asq - 2AB + Bsq

i took the sq from the ecuation because it was in both sides as well as -9/2

 

[whaahppnd]

That's your problem. This is not "simple algebra." You can't "take away" the sq from both sides.
As I said before suppose you have (1)^2=(-1)^2. You cannot simply "take away" the sq and say that 1=-1. Do you see that you are losing a root?

 

[Tomkraven]

actually u can; cause when u do the root of a squared number the answer is both the negative and positive forms of the same number.

 

[whaahppnd]

actually u can; cause when u do the root of a squared number the answer is both the negative and positive forms of the same number.

What math class are you in?
The reason you have stated is exactly why you can't just take the sqrt.

Which part are you confused about?
Just because x^2=y^2 does not mean x=y
i.e. (4-9/2)^2=(5-9/2)^2 does NOT imply 4-9/2=5-9/2

 

[Tomkraven]

ok... i wont discuss about this anymore... please any mod come and close the thread

 

[whaahppnd]

yea i agree its not for the debate hall
just ask a math teacher to explain it to you

 

[AltF4]

Come on.

I have a thread in the Pool Room for this. With a lot more examples, too. That one is one of the least convincing. I have some that you REALLY need to know your stuff to identify the error in. Not just simple square root errors.

I think I called it "1=2" or something like that. Just do a search for it.

 

[Osco316]

Yeah, yeah, alt. We all know you're a friggin' genius.