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Trouble with de morgans law and boolean algebra

So Ive attached an example of a couple of questions from a past exam paper. But, I have no idea how the answers can be achieved. If anyone can take a look, and explain step by step how to achieve each answer, that would be great, as I've tried and still dont get it :-|

Thanks in advance

Attachment 30985

Re: Trouble with de morgans law and boolean algebra

Do you know what these things **mean**? What does "$\displaystyle \overline{A}$" *mean*? What does "A+ B" *mean*? What does "$\displaystyle A\cdot B$" *mean*?

Re: Trouble with de morgans law and boolean algebra

I know that " \overline{A}" means "not A" and "A+ B" means "A or B" and " A\cdot B" means "A and B" but I still have trouble with arriving at the answer

Re: Trouble with de morgans law and boolean algebra

use the following

for first part B.(A+COMP(A))

U KNOW A+COMP(A)=1

AND B.1=B

FOR SECOND PART TAKE OUT B AS COMMON

U GET B(1+A)

1+A=1 AND B.1=B

FOR THIRD PART COMP(X+Y)=COMP(X)COMP(Y)

HERE X=B AND Y=COMP(A)+COMP(B)

SO COMP(X)COMP(Y) IS GIVEN FIND COMP(X+Y)

COMP(X+Y)=COMP(B+COMP(A)+COMP(B))

NOW B+COMP(B)=1 AND 1+COMP(A)=1

ALSO COMP(1)=0