# Union Complement question

• Oct 1st 2008, 07:30 PM
kathrynmath
Union Complement question
I have \$\displaystyle (A intersect B)'\$
I want an equivalent statement shown using Venn diagrams. I am lost. I know I need a Venn diagram showing A and B minus the intersection plus all of the outside. A' intersect B' gives all of outside. So how do I get outside and A and B minus the intersection?
• Oct 1st 2008, 07:46 PM
icemanfan
(A n B)' = A' u B' could be one way of looking at this problem. Basically you shade everything except A n B. So all of A except the part that intersects with B, all of B except the part that intersects with A, and everything outside of both A and B.
• Oct 1st 2008, 07:50 PM
kathrynmath
Quote:

Originally Posted by icemanfan
(A n B)' = A' u B' could be one way of looking at this problem. Basically you shade everything except A n B. So all of A except the part that intersects with B, all of B except the part that intersects with A, and everything outside of both A and B.

Yeah, that's what I got for ( A intersect B)'. my problem is A' U B'. So, that would give anything's that's not A and B. So, that would give verything outside of A and B, right? But I need something that also includes A and B minus the intersection.
• Oct 1st 2008, 08:03 PM
icemanfan
I was trying to say that (A n B)' is the same as A' u B', but you still seem uncertain. Remember that A' includes some of B and B' includes some of A.
• Oct 1st 2008, 08:06 PM
kathrynmath
Oh, ok I see now. So I could do a venn diagram of A', a Venn diagram of B' and then combine them,.
• Oct 1st 2008, 08:11 PM
icemanfan
Quote:

Originally Posted by kathrynmath
Oh, ok I see now. So I could do a venn diagram of A', a Venn diagram of B' and then combine them,.

Exactly right.