# some basic set questions

• Jul 13th 2009, 07:42 AM
thereddevils
some basic set questions
(1) Is (B n A) n (A' u C') equivalent to B n [ A n (A' n C')] ??

If so , what law is that ? Distributive laws ?

(2) why is A' n (A' u B) = A' ??

Can someone explain the above 2 questions to me .. Thanks a lot !!
• Jul 13th 2009, 07:59 AM
Plato
Quote:

Originally Posted by thereddevils
(2) why is A' n (A' u B) = A' ??

You should know $P \subseteq Q\; \Rightarrow \;P \cap Q = P$

Then observe that $A' \subseteq A' \cup B$.
• Jul 13th 2009, 08:05 AM
thereddevils
Thanks Plato , i got it . How about (1) ?
• Jul 13th 2009, 08:17 AM
Plato
Quote:

Originally Posted by thereddevils
Let $X=B\cap A$ then $X\cap(A'\cup C')=(X\cap A')\cup (X\cap C')$