How to prove (not show) that 1+1=2

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- Feb 25th 2010, 11:53 AMMukilabProve 1+1=2
How to prove (not show) that 1+1=2

- Feb 25th 2010, 11:59 AMQuacky
I'm not sure I understand. There is not a proof needed. Is that not almost the very definition of two?

- Feb 25th 2010, 12:14 PMnikhilmy thinking
I guess 1+1=2 is a convention.

if a single entity is called 1 (conventionally) then its double will be called 2(conventionally). since two quantities are individually single therfor 1+1=2 must hold. [for this operation of addition is also defined conventionally.]

this question is similar to the question why B comes after A.(even it is a convention) - Feb 25th 2010, 01:17 PMMukilab
- Feb 25th 2010, 01:53 PMArchie Meade
$\displaystyle x+x=(x+x)=2(x)$

A unit added to a unit is two of the same unit, by definition.

$\displaystyle =$ means "what is before" is the same as "what is after".

If $\displaystyle x=1,$

$\displaystyle 1+1=2(1)=2$

This proof requires the definition that the "symbol" 2 represents two of the same unit,

whatever that unit may be. - Feb 25th 2010, 02:23 PMDrexel28