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Q&A #267


An algebraic "proof" that 2 = 1

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From: Claudia (for Teacher2Teacher Service)
Date: May 13, 1998 at 22:25:07
Subject: Re: Algebra proof

Sorry it has taken me so long to reply, but I couldn't locate the proof you 
wanted 
until today!

Start off with              a = b
then multiply by a        a^2 = ab
subtract b^2        a^2 - b^2 = ab - b^2
factor             (a+b)(a-b) = b(a-b)
divide (a-b)            a + b = b
substitute              b + b = b
simplify                   2b = b
divide by b                 2 = 1

Of course there are errors in the process that allow for division by zero (a-
b) 
since a = b.

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