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## #1 2013-11-13 21:02:28

Debanjan
Member
Registered: 2013-11-13
Posts: 4

### My question on set theory

let there be two sets A and B.

IF A=B then is A union B = A intersection B ??

I would love to know your logic behind the same.

Note : A and B can be any two types of sets.

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## #2 2013-11-14 04:06:31

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: My question on set theory

Hi Debanjan;

If the two sets are equal then the union of them is the set itself and the intersection of them is the set itself so the answer is yes.

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #3 2013-12-15 22:12:51

rahat
Member
Registered: 2013-12-15
Posts: 1

### Re: My question on set theory

very difficult

i am no mathematician

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## #4 2013-12-15 22:34:35

bobbym
bumpkin
From: Bumpkinland
Registered: 2009-04-12
Posts: 109,606

### Re: My question on set theory

Hi rahat;

What do you not understand?

In mathematics, you don't understand things. You just get used to them.
If it ain't broke, fix it until it is.
Always satisfy the Prime Directive of getting the right answer above all else.

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## #5 2013-12-15 23:45:10

bob bundy
Moderator
Registered: 2010-06-20
Posts: 7,969

### Re: My question on set theory

hi rahat,

Welcome to the forum.

A picture speaks a thousand words.  See below (click to make bigger).

The blue region is A intersect B.

The union is all in both circles.

Now what happens if you slide one circle so it coincides with the other?

Bob

Children are not defined by school ...........The Fonz
You cannot teach a man anything;  you can only help him find it within himself..........Galileo Galilei

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