# Math Optical Illusion

Try to figure this one out! How is it possible that two is equal to one, when we all know that that isn't true. Try to spot the mistake one of the twins made!

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Views: 15,632
• Mime
• May 5, 2009, 1:59 am
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• 7

Both variables would have to be zero for this to actually be true, but it's still false. In (a+b)(a-b) = b(a-b), you would divide (a-b) by both sides. Since both variables are 0, (a-b) would equal 0, therefore, you would be dividing by zero breaking one of the fundamental rules of algebra.

• 4

fancy but u could have just said u cant divide by zero lol

• 2

Confuzzled...

• fellage
• October 11, 2009, 6:37 am
• 2

they leave out the fact that (a-b)=0
so (a+b)(a-b)=b(a-b) is actually (a+b)(0)=b(0)
so 0=0

• 2

Aren't you still trying to get people here to believe you're 10?

• Ruleb
• April 6, 2010, 4:36 pm
• 2

That's quite similar to this:

This one isn't true though because you can't divide by zero.

• 1

a+a=a is false because it dosent staqte the variable for the a or b so you should be able to plug in any number for a or b

• mit8818
• October 11, 2009, 10:50 am
• 1

As Krandon says, this wouldn't work as you're diving by 0. So you're ultimately proving 0=0. Which we already knew :3

• Tyro
• October 11, 2009, 11:44 am
• 1

(a+b)=b is not a+a=a, but a=0

• Phoenix
• December 22, 2009, 7:43 am
• 1

My brain asplodes

• Ertrov
• December 22, 2009, 9:42 am
• 1

2a=a

• 1

so much crap doesnt make sense in math andthis... is just 1

• xiclown
• December 23, 2009, 8:05 am
• 1

(a+b) doesn't equal b

• Bekenel
• December 23, 2009, 8:09 am
• 1

well im rubbish at maths so i wont get this lol but im sure it would be good in a way :P +3

• 1

i agree

• Simmo49
• January 16, 2010, 12:31 am
• 1

The error is the last of line 4 when they divide both sides by (a-b).
If a = b like they stated then you have a division by 0 error.

• peace
• April 6, 2010, 1:37 pm
• 1

Kradon got the best explanation. Cancelling (a-b) is done by dividing both sides by (a-b), which is zero because of the given (a=b). So statements from (a+b)=a and below are invalid.

• 1

yeah i fuckin hate algebra because it makes me want to turn in every essay and other papper in binnary

• 1

2A=A...but the last step he is assuming that A = any real number but when solving for A, you have to subtract A from both sides to get A=0. but the problem is assuming that A and B is a subset of all real numbers.

• Mizuno
• July 25, 2010, 8:38 pm
• 1

well, at the end you just have 'a' and they say there that it's equal to '1'.. but if you go back and plug 1 in for a, it screws up the equation around the 4th step.. in other words, this problem is simply: FALSE

• Stoy
• July 25, 2010, 9:26 pm
• 1

are you asian cuz im asian and i didnt get that fucking problem

• gryxng
• July 25, 2010, 11:05 pm
• 1

I think that the twins are doing shrooms, because it is an optical illusion and the whole equation and process together looks like a mushroom

• cary139
• September 10, 2010, 1:03 pm
• 1

substitute 1 for a and b, the inequality comes from the long part

• 0

damn twins..only twins their ever should be is those hot twins from the beer commericals or just girl twins in general =]

• 0

i dont get it..but i kinda dont care bcus this is pointless

• 0

gtfo

• YaTeSeY
• December 26, 2009, 3:50 pm
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