Exercise · ZW-RELATIVE-COMPLEMENT-006 · ★★☆ Intermediate
Which statement is true for any sets \(A\) and \(B\)?
Choose one option.
A \(A \setminus B = B \setminus A\) B \(A \setminus B = A \cup B\) C \(A \setminus B \subseteq B\) D \(A \setminus B = A \setminus (A \cap B)\)
Show answer D. \(A \setminus B = A \setminus (A \cap B)\)
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Explanation An element of \(A\) is not in \(B\) if and only if it is not in \(A \cap B\), so both expressions agree. Equality with \(B \setminus A\) fails in general.
The relative complement of \(B\) in \(A\) is the set \(A \setminus B\) of elements of \(A\) that do not belong to \(B\).
\[A \setminus B = \{x \in A : x \notin B\}\]
More practice problems: relative complement ZW-RELATIVE-COMPLEMENT-001 What does x ∈ A setminus B mean?ZW-RELATIVE-COMPLEMENT-002 If A = \a,b,c\ and B = \b\, what is A setminus B?ZW-RELATIVE-COMPLEMENT-003 What is A setminus A?ZW-RELATIVE-COMPLEMENT-004 What relation does A setminus B satisfy with A?ZW-RELATIVE-COMPLEMENT-005 Let A = \1,…,10\ and B = \2,4,6,8,10,12\. What is A setminus B?ZW-RELATIVE-COMPLEMENT-007 How many elements does \2,4\ setminus A have, if A = \1,2,3,4\?ZW-RELATIVE-COMPLEMENT-008 If A setminus B = ∅, what can be concluded?ZW-RELATIVE-COMPLEMENT-009 Let A = \1,…,20\, B_1 = A setminus \x : x is even\ and B_2 = A setminus B_1. What is B_2?