Math Is Fun Forum

javadude

Member

Registered: 2008-07-13

Posts: 6

Discrete Math - Proofs by Set Identities

Hey everyone, Im taking a course in Discrete math and am having a hard time with some of these topics.  For instance,  Im given

(A ∪ C) ∩ [ (A ∩ B) ∪ (C' ∩ B) ] = A ∩ B

Im asked to prove this by set identities.  Ive made the first step using the distributive property to achieve

(A ∪ C) ∩ (A ∩ B) ∪ (A ∪ C) ∩ (C' ∩ B)

Now, I can see im obviously suppose to somehow get C and C' together so they cancel out to a null set.  Im lost as to what direction to take?  Can someone lend a helping hand?

Thanks alot in advance!

JaneFairfax

Member

Registered: 2007-02-23

Posts: 6,868

Re: Discrete Math - Proofs by Set Identities

Last edited by JaneFairfax (2008-07-13 12:50:09)

javadude

Member

Registered: 2008-07-13

Posts: 6

Re: Discrete Math - Proofs by Set Identities

wow... I can't believe how stupid I feel now... its so obvious.  I suppose it always is though once you see it done.

Thanks alot JaneFairfax, now onto combinatorics