1. **Problem Statement:** Solve the first question: Distinguish between set intersection and set union. 2. **Definitions:** - The **intersection** of two sets $A$ and $B$, denoted $A \cap B$, is the set of all elements that are in both $A$ and $B$. - The **union** of two sets $A$ and $B$, denoted $A \cup B$, is the set of all elements that are in $A$, or in $B$, or in both. 3. **Explanation:** - Intersection finds common elements. - Union combines all elements without duplication. 4. **Example:** If $A = \{1, 2, 3\}$ and $B = \{2, 3, 4\}$, then $$A \cap B = \{2, 3\}$$ $$A \cup B = \{1, 2, 3, 4\}$$ **Final answer:** - Set intersection $A \cap B$ is the set of elements common to both $A$ and $B$. - Set union $A \cup B$ is the set of all elements in $A$ or $B$ or both.