Core idea
Use roster or set-builder notation. Union combines elements; intersection keeps common elements; complement is relative to a stated universal set.
Worked check
If A={1,2,3}, B={3,4}, then A∩B={3} and A∪B={1,2,3,4}.
Practice
- Show each step and state any domain or assumption.
- Check the result by substitution, estimation or a second method.