Tuesday, October 14, 2008

2 is 1

A discussion over at Good Math, Bad Math reminded me of this - My favorite math riddle:

Proof that 2 = 1

Start with: X = Y
multiply both sides by X: X*X = X*Y
subtract Y^2 from both sides: X^2 - Y^2 = X*Y - Y^2
do some factoring: (X+Y)*(X-Y) = Y*(X-Y)
divide both sides by (X-Y): (X+Y) = Y
substitute Y for X: (Y+Y) = Y
divide by Y and simplify: 2 = 1

There you have it, a mathematical proof that two is equal to one!