Practice problem
Let A={1,4,−2,27}A = \{1, 4, -2, 27\}A={1,4,−2,27}. Which of the following statements about set intersections are true?
A∩A=AA \cap A = AA∩A=A
A∩N={1,4,27}A \cap \mathbb{N} = \{1, 4, 27\}A∩N={1,4,27} (Remember, N\mathbb{N}N is the set of natural numbers.)
A∩R=∅A \cap \mathbb{R} = \varnothingA∩R=∅ (Remember, R\mathbb{R}R is the set of real numbers.)
A∩∅=AA \cap \varnothing = AA∩∅=A
For any set BBB, A∩B=B∩AA \cap B = B \cap AA∩B=B∩A
For any sets BBB and CCC, A∩(B∩C)=(A∩B)∩CA \cap (B \cap C) = (A \cap B) \cap CA∩(B∩C)=(A∩B)∩C
For any set BBB, A∩B≠BA \cap B \not= BA∩B=B
Type a concept, like “slope” or “photosynthesis”.