# Great Mathematics...

Discussion in 'The Lighter Side of Being a DBA' started by ghemant, Feb 9, 2006.

1. ### ghemantModerator

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............

Hemantgiri S. Goswami
ghemant@gmail.com
"Humans don't have Caliber to PASS TIME , Time it self Pass or Fail Humans" - by Hemantgiri S. Goswami

3. ### FrankKalisModerator

I think I'm going to tell that to my bank next time. [<img src='/community/emoticons/emotion-2.gif' alt='' />]<br /><br />--<br />Frank Kalis<br />Microsoft SQL Server MVP<br /<a target="_blank" href=http://www.insidesql.de>http://www.insidesql.de</a><br />Heute schon gebloggt?<a target="_blank" href=http://www.insidesql.de/blogs>http://www.insidesql.de/blogs</a><br />
4. ### mmarovicActive Member

mssql server would report divide by zero exception [<img src='/community/emoticons/emotion-1.gif' alt='' />]

I thought (a+b)(a+b) = a*a + 2ab + b*b - but I'm not really good at maths.

a*a + 2ab + b*b = ca + cb

4*4 + 2*4*6 + 6*6 = 6*2 + 6*4

16 + 48 + 36 = 12 + 24

100 = 36 - nah, I don't think so.
6. ### FrankKalisModerator

Well, a*a + 2ab + b*b is certainly equivalent to a*a + ab + ba + b*b. But you have some typos in your formula. Anyway, think about Mirko's comment. [<img src='/community/emoticons/emotion-1.gif' alt='' />]<br /><br /><br />--<br />Frank Kalis<br />Microsoft SQL Server MVP<br /<a target="_blank" href=http://www.insidesql.de>http://www.insidesql.de</a><br />Heute schon gebloggt?<a target="_blank" href=http://www.insidesql.de/blogs>http://www.insidesql.de/blogs</a><br />

Like I said, I wasn't really good at maths.

Not sure if this is equivalent to (a+b)(a+b) - someone care to explain this?

a*a + ab + ba + ! b*b

9. ### mmarovicActive Member

The problem is here: a( a + b -c) == -b(b + a - c)
a+b-c = 0 so any x * 0 = y * 0, so it is not equivalent to x = y.
The rule is: t <> 0 => (x*t = y*t <=> x=y)

10. ### FrankKalisModerator

q.e.d [<img src='/community/emoticons/emotion-1.gif' alt='' />]<br /><br />--<br />Frank Kalis<br />Microsoft SQL Server MVP<br /<a target="_blank" href=http://www.insidesql.de>http://www.insidesql.de</a><br />Heute schon gebloggt?<a target="_blank" href=http://www.insidesql.de/blogs>http://www.insidesql.de/blogs</a><br />
11. ### mmarovicActive Member

Frank, are you mathematician too? [<img src='/community/emoticons/emotion-1.gif' alt='' />]
12. ### FrankKalisModerator

Not by profession. Actually I'm more into Financial Mathematics and Statistics. But I love such puzzles. [<img src='/community/emoticons/emotion-1.gif' alt='' />]<br /><br />Are you a mathematician?<br /><br />--<br />Frank Kalis<br />Microsoft SQL Server MVP<br /<a target="_blank" href=http://www.insidesql.de>http://www.insidesql.de</a><br />Heute schon gebloggt?<a target="_blank" href=http://www.insidesql.de/blogs>http://www.insidesql.de/blogs</a><br />

Phew - I had to dig pretty deep into my memory banks here! One can take only so much maths on any given day. Or another.
14. ### mmarovicActive Member

Sort of. I graduated computer science on faculty of mathematics. We actually studied mathematic much more then computer science. However, after graduation I didn't have much opportunity to apply my math knowledge, so right now I don't remember much of what I've learned for years [<img src='/community/emoticons/emotion-6.gif' alt='' />]

As a+b=c
a + b -c=0
So you cant divide 0 on two sides of the equation

Failing to plan is Planning to fail
16. ### Luis MartinModerator

Funy once on vacation.

Of course you can divede by 0 in any case.
That is a good example why.

So when you simplify (a + b -c) whit (b + a - c) your are diveding by 0, and that is the joke.

Luis Martin
Moderator
SQL-Server-Performance.com

Although nature commences with reason and ends in experience it is necessary for us to do the opposite, that is to commence with experience and from this to proceed to investigate the reason.
Leonardo Da Vinci

Nunca esperes el reconocimiento de tus hijos, eso ocurrirÃ¡ luego de tu muerte

All postings are provided â€œAS ISâ€ with no warranties for accuracy.

I got the joke - I think - a few posts up from here already.

The fun bit is that he's adding the (a+b) on both sides., then deduces both sides to 0, which isn't the object of the whole excercise anyway. Yeah, great fun - ah um.

Mathematician is correct if this is correct

1*0=0
2*0=0
1*0=2*0
1=2