Let A = {1, 2, 4, 5} B = {2, 3, 5, 6} C = {4, 5, 6, 7}. Verify the following identities: (i) A ∩ (B – C) = (A ∩ B) – (A ∩ C) (ii) A – (B ∪ C) = (A – B) ∩ (A – C)
Let A = {1, 2, 4, 5} B = {2, 3, 5, 6} C = {4, 5, 6, 7}. Verify the following identities: (i) A ∩ (B – C) = (A ∩ B) – (A ∩ C) (ii) A – (B ∪ C) = (A – B) ∩ (A – C)

Answers:

(i) 

LHS,

B–C = {x  B: x ∉ C}

B = {2, 3, 5, 6}

C = {4, 5, 6, 7}

B–C = {2, 3}

(A ∩ (B – C)) = {x: x  A and x  (B – C)}

(A ∩ (B – C)) = {2}

RHS,

(A ∩ B) = {x: x  A and x  B}

(A ∩ B) = {2, 5}

(A ∩ C) = {x: x  A and x  C}

(A ∩ C) = {4, 5}

(A ∩ B) – (A ∩ C) = {x  (A ∩ B): x ∉ (A ∩ C)}

(A ∩ B) – (A ∩ C) = {2}

∴ LHS = RHS

Thus, Verified.

(ii)

LHS,

(B ∪ C) = {x: x  B or x  C}

(B ∪ C) = {2, 3, 4, 5, 6, 7}.

A – (B ∪ C) = {x  A: x ∉ (B ∪ C)}

A = {1, 2, 4, 5}

(B ∪ C) = {2, 3, 4, 5, 6, 7}

A – (B ∪ C) = {1}

RHS,

A – B = {x  A: x ∉ B}

A = {1, 2, 4, 5}

B = {2, 3, 5, 6}

A – B = {1, 4}

A – C = {x  A: x ∉ C}

A = {1, 2, 4, 5}

C = {4, 5, 6, 7}

A – C = {1, 2}

(A – B) ∩ (A – C) = {x: x  (A – B) and x  (A – C)}.

(A – B) ∩ (A – C) = {1}

∴ LHS = RHS

Thus, verified.