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#1 2009-04-15 00:03:32

Shmeeztut
Member
Registered: 2009-04-14
Posts: 2

Impossible Algebra?

My friend told me about this, and I just don't get how it works!

x = y

Times x to both sides.

x² = xy

Times -y^2 to both sides.

x² - y² = xy - y²

Factorise.

(x + y )(x - y) = y(x - y)

Then... divide both sides by (x - y).

x = x + y?!

How is this possible? The algebra is correct as far as I can see.








da frend hu told mi is super cool and awesome

Last edited by Shmeeztut (2009-04-15 00:06:05)

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#2 2009-04-15 00:10:26

LuisRodg
Real Member
Registered: 2007-10-23
Posts: 322

Re: Impossible Algebra?

Algebra is not correct. Since x = y then x - y = 0 so when you divide by x - y you are dividing by 0 which is not allowed in math. Thats the mistake.

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