Long ago, a clever mathematician used to cheat people.
Once he borrowed $4000.00 from a rich man. After a few
days, he borrowed $2000.00 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 he had
already paid 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, but 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)
=> aa + ab + ba + bb = ca + cb
=> aa + ab - ca = cb - bb - ba
=> a( a + b -c) = -b(b + a - c)
so a = -b
=> a + b = 0
Hence by putting the values of “a” and “b” as 4000 and
2000 respectively, their sum is zero, so the
mathematician saw no need to pay any money to the rich
man. The above calculation has no doubt surprised you
as it did the judge.
