MaTHemaTics.!!!!!

Long ago, a mathematician used to cheat people. Once
> he borrowed
> Rs.4000/- from a rich man. After a few days, he
> borrowed Rs.2000/- from the same man.
>
> Many days passed, the mathematician did not return
> the
> money to the rich man. The rich man went to the
> mathematician and asked to return the money.
>
> But to his great surprise, the mathematician replied
> that there is no
> need to pay the debt.
>
> "See here, friend" said the mathematician " the sum
> of
> 4000 and 2000 is equal to
> zero, so I do not have any balance to pay".
>
> The rich man took the matter to the court. When the
> judge came to know
> this, he was astonished. He asked the mathematician
> to
> prove that sum of 4000 and 2000 is zero, and not
> 6000.
>
> The Clever mathematician agreed. He said:
>
> let a == 4000, b == 2000 and c == 6000
>
> a + b == c
>
> Multiply both sides by a + b
>
> (a + b) (a + b ) == c (a + b)
>
> a*a + ab + ba + b*b == ca + cb
>
> a*a + ab - ca == cb - b*b - ba
>
> a( a + b -c) == -b(b + a - c)
>
> so a == - b
>
> a + b == 0
>
> Hence 4000 + 2000 = 0............
>
>
>
>
>
>