UGC NET CSE | December 2019 | Part 2 | Question: 3

Question

The Boolean expression $AB+A \overline{B}+\overline{A}C+AC$ is unaffected by the value of the Boolean variable _________.

• A. $A$
• B. $B$
• C. $C$
• D. $A, B$ and $C$

Answer 1

Let f=AB+AB’+A’C+AC

       =A(B+B’)+C(A+A’)

       =A(1)+C(1)

       =A+C

So,it is unaffected by the value of B

option(2)

Answer 2

Here f(A,B,C)=AB+AB'+AC+A'C

After minimzation we get f= A+C that means f is independent from var. B .

In other word ,here var. B is useless or dummy var(not standard term)