Q6 of 50 Page 14

Given that U = {a, b, c, d, e, f, g, h}, A = {a, b, f, g}, and B = {a, b, c}, verify De Morgan’s laws of complementation.

We know that De Morgan’s laws of contemplation are:


(a) (A B)’ = A’ B’


(b) (A B)’ = A’ B’


Case (a):


First, we shall verify (a). To do this, we consider


A B = {a, b, f, g} {a, b, c} = {a, b, c, f, g}


(A B)’ = U {a, b, c, f, g} = {d, e, h} … (1)


Now, A’ = U A = {c, d, e, h}


B’ = U B = {d, e, f, g, h}


Then, A’ B’ = {c, d, e, h} {d, e, f, g, h} = {d, e, h} … (2)


From (1) and (2), it follows that (A B)’ = A’ B’.


Case (b):


Next, we shall verify (b). To do this, we consider


A B = {a, b, f, g} {a, b, c} = {a, b}


(A B)’ = U {a, b} = {c, d, e, f, g, h} … (3)


Now, A’ = U A = {c, d, e, h}


B’ = U B = {d, e, f, g, h}


Then, A’ B’ = {c, d, e, h} {d, e, f, g, h} = {c, d, e, f, g, h} … (4)


From (3) and (4), it follows that (A B)’ = A’ B’.


Hence, De Morgan’s laws of contemplation are verified.


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