Top definition
The person before made a mistake in their proof.
1. x = y
2. xy = y^2
3. xy - x^2 = y^2 - x^2
4. x(y - x) = (y + x)(y - x)
So far so good.
4.5. x = (y + x)(y - x)/(y - x) is what they did to get to step 5, which says:
5. x = y + x

This is wrong though. since x = y, y -x = 0, and so you can't divide by y - x.
Anyone who says 1 = 2 is wrong.

1 != 2
by mathisfun March 17, 2008

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2
1. x = y
2. xy = y^2
3. xy - x^2 = y^2 - x^2
4. x(y - x) = (y + x)(y - x)
5. x = y + x
6. x = x + x
7. x = 2x
8. 1 = 2

QED
As proven, 1 = 2, thus 0 = 1, etc. And so for any number i, there is an equivalent j that is not equal to i.

This is further explained in the Identity Theft Theorem.
by SAH aka the GSH October 16, 2006

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One side has the word, one side has the definition. Microwave and dishwasher safe. Lotsa space for your liquids.