# Re: "Prove" 2=1

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Posted by Denis Borris on November 11, 2002 at 07:44:10:

In Reply to: "Prove" 2=1 posted by MathBard on November 11, 2002 at 01:20:11:

: I saw a basic Algebra problem once that gave the illusion that 2=1,
:after doing normal inverse operations and properties of equality steps.
: I know it camoaflagued zero as a variable somehow then divided by that
: variable, but it isn't obvious to the beginner that said variable is actually zero.
:DOES ANYONE KNOW THIS PROBLEM WENT? I can't seem to remember anymore than I have shared. (All the steps need to be understandable to Algebra I students).

Hmmmm....isn't "I can't seem..." something that makes Billy Shakespeare
roll over in his grave? :)

let a = b

aČ = ab

Multiply both sides by a
aČ + aČ - 2ab = ab + aČ - 2ab

Add (aČ - 2ab) to both sides
2(aČ - ab) = aČ - ab

Factor the left, and collect like terms on the right
2 = 1

Divide both sides by (aČ - ab)

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