1. Prove that if A U B = A and A intersect B = A then A = B

2. Show that is general (A-B) U B is not A

3. Let A = {2,4,...,2n} and B = {3,6,...,3n}. Find A-B

2. 1. $A \cup B = A \implies B \subseteq A$
$A \cap B = A \implies A \subseteq B$
It follows that ...
2. Let $A = \{1,2,3\}, B=\{1,2,3,4\}$ then $(A \backslash B) \cup B \neq A$
It is true if $B \subseteq A$
3. Take out multiples of 6.