Is 1 = 2 ? ;)

start with this

>> a = b

>> ab = b²...................... [multiply by b on both sides]

>> ab - a² = b² - a² ... [sub a² from both sides]

>> a(b-a) = (b+a) (b-a).. [factorise]

>> a = (b+a) .....................................[divide by (b-a) ]

>> a = a+a........................................... [substitue a=b ]

>> a = 2a ...............................................[simplify]

>> 1 = 2 ....................................................[divide by a]

^{hence proved :)}