Let A = {a, b, c}, B = {b, c, d, e} and = {c, d, e, f} be subsets of U = {a, b, c, d, e, f}. Then verify that:

(i) (A’)’ = A


(ii) (A B)’ = (A’ B’)


(iii) (A B)’ = (A’ B’)



(i) A’ = {d, e, f}


(A’)’ = {a, b, c} = A


Hence proved


(ii) AB = {a, b, c, d, e}


(AB)’ = {f}


A’ = {d, e, f}


B’ = {a, f}


A’B’ = {f}


(AB)’ = (A’B’)


Hence proved


(iii) A’B’ = {a, d, e, f}


AB = (b, c}


(AB)’ = {a, d, e, f}


(AB)’ = A’B’


Hence proved


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