My ALevel maths teacher was fond of that one (though he missed out the obvious middle conclusion of a=0).
ah but there is a flaw in your argument!
(ab) = 0 and by simplifying the equation (a+b)(ab) = b(ab) to (a+b) = b you're performing a division by zero, which renders the whole equation undefined.
From: (Anonymous) 20060128 01:30 pm (UTC)
 (Link)

Quite right, but I never claimed it was a correct proof :) All of these sorts of "proofs" use something like that which looks perfectly OK 'till you investigate it more deeply.
My head hurts! But I think the hidden meaning is that you've been playing with your pint and quart pots again! Hint  try variable density material  but don't get too extreme with it... black holes are very hard to sweep under the carpet  just like black cats  and the event horizon  well... just be carefull there!
From: (Anonymous) 20060128 01:26 pm (UTC)
 (Link)

The "trick" is getting (ab) on each side and then dividing by it since it is zero! Most of these sorts of "proofs" use that in some form or the other.
Errrr......... I seem to remember something about dividing by zero being good for the resultant cost of ink as you try to write the answer down.... hello... is that how we got the bomb?
I love these proofs but the logic side of them makes me want to scream! I once diddled with the LorentzFitzgerald equation  in a maths friendly way  to see what happened and it looked good at about 34C  but definitely not so good any faster! 