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I was mathematically shown 1 = 2 by a function that states the following

$$x^2-x^2 = x^2-x^2 $$ $$x(x-x)=(x-x)(x+x)$$

dividing by $(x-x)$ we get...

$$x=x+x$$ $$ x=2x$$ $$1=2$$

I can see that mathematically he was right, but for sure that I was missing something as it doesn't make mathematical sense

fady taher
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    Mathematically, it is wrong. $x-x=0$, and division by $0$ isn't allowed. – Clayton Jul 28 '15 at 16:29
  • Cute, but invalid. – hardmath Jul 28 '15 at 16:35
  • Remember that multiplying anything with zero is zero – Hoping_Blessing Jul 28 '15 at 16:36
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    Here's a shorter "fake proof:" $0\times1=0\times2$. Dividing out by $0$, we get $1=2$. This is essentially what your "proof" is doing, but your "proof" hides it more. – Akiva Weinberger Jul 28 '15 at 16:40
  • @columbus8myhw I don't see how OP's proof "hides it more"--this is one of the most abysmal fake proofs I have ever seen. Usually the flaw in dividing by zero is hidden somewhere and your goal is to track it down. Here it's just like, "Hey, divide by $x-x$," where it is very clear you are dividing by $0$. – Daniel W. Farlow Jul 28 '15 at 16:43
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    @DanielW.Farlow It hides it slightly more, but the difference between the two proofs is smaller than $\epsilon$ for any $\epsilon>0$ :P – Akiva Weinberger Jul 28 '15 at 16:45
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    I don't really understand why this question attracted so many downvotes. Yes, of course the answer is obvious to most of us, but aren't simple questions allowed? I don't think the question was asked in a poor way. – Eff Jul 28 '15 at 16:58

3 Answers3

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So this does not go unanswered...as others have mentioned, the obvious error is that you are dividing by $0$ by when you divide by $x-x$. Thus, whatever conclusion you reach is most certainly flawed.

The irksome thing in this case is that the flaw is hardly subtle. I would recommend you see this post for a much more interesting attempt to fool readers into thinking $0=1$.

Community
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Daniel W. Farlow
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0/0 is not equal to 1

You assumed it to be 1 when you divided by (x-x)

Prakash
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0

When it shows x(x-x) it is not adding x to 0 it is multiplying. In basic maths you learn that 5(7-2) is the same as 5 multiplied by (7-2)

Bob
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