Set theory/Simple rules/Exercise

Let ${}A,B$ and ${}C$ denote sets. Prove the following identities.

1. ${}A\cup \emptyset =A\,,$

2. ${}A\cap \emptyset =\emptyset \,,$

3. ${}A\cap B=B\cap A\,,$

4. ${}A\cup B=B\cup A\,,$

5. ${}A\cap (B\cap C)=(A\cap B)\cap C\,,$

6. ${}A\cup (B\cup C)=(A\cup B)\cup C\,,$

7. ${}A\cap (B\cup C)=(A\cap B)\cup (A\cap C)\,,$

8. ${}A\cup (B\cap C)=(A\cup B)\cap (A\cup C)\,,$

9. ${}A\setminus (B\cup C)=(A\setminus B)\cap (A\setminus C)\,.$

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