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If A and B be two sets such that n(A) = 3, n(B) = 4 and n(A ∩ B) = 2 then find. (i) n(A × B) (ii) n(B × A) (iii) n(A × B) ∩ (B × A) |
Answer» Given: n(A) = 3, n(B) = 4 and n(A ∩ B) = 2 (i) n(A × B) = n(A) × n(B) ⇒ n(A × B) = 3 × 4 ⇒ n(A × B) = 12 (ii) n(B × A) = n(B) × n(A) ⇒ n(B × A) = 4 × 3 ⇒ n(B × A) = 12 (iii) n((A × B) ∩ (B × A)) = n(A × B) + n(B × A) – n((A × B) ∪ (B × A)) n((A × B) ∩ (B × A)) = n(A × B) + n(B × A) – n(A × B) + n(B × A) n((A × B) ∩ (B × A)) = 0 |
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