Verify A − (B∩C) = (A − B)∪(A − C)
Question:
Let \[ A=\{1,2,4,5\},\quad B=\{2,3,5,6\},\quad C=\{4,5,6,7\} \] Verify the identity: \[ A-(B\cap C)=(A-B)\cup(A-C) \]
Solution
First find \( B\cap C \):
\[ B\cap C=\{5,6\} \]Now find \( A-(B\cap C) \):
\[ A-(B\cap C) = \{1,2,4,5\}-\{5,6\} \] \[ A-(B\cap C)=\{1,2,4\} \]Now find \( A-B \):
\[ A-B = \{1,2,4,5\}-\{2,3,5,6\} \] \[ A-B=\{1,4\} \]Next find \( A-C \):
\[ A-C = \{1,2,4,5\}-\{4,5,6,7\} \] \[ A-C=\{1,2\} \]Now find \( (A-B)\cup(A-C) \):
\[ (A-B)\cup(A-C) = \{1,4\}\cup\{1,2\} \] \[ (A-B)\cup(A-C)=\{1,2,4\} \]Therefore,
\[ A-(B\cap C)=(A-B)\cup(A-C) \]Hence verified.