GATE CSE 1999 | Question: 1.8

Question

Which of the following functions implements the Karnaugh map shown below?

• A. $\bar{A}B + CD$
• B. $D(C+A)$
• C. $AD+\bar{A}B$
• D. $(C+D) (\bar{C}+D) + (A+B)$

Comments

We aren't considering the X's here because it goes against the goal of simplification - which is to reduce to as few terms as possible. By adding the quad with X's (by considering them as 1s), we will be increasing terms unnecessarily.

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pritishc yeah, like we “don't care” about them…

Answer 1

$CD+AD$

$=D(C+A)$

Correct Answer: $B$

Answer 2

Answer - B.

$CD+AD$

Comments

how the answer is B,

    after solving the given k map we get

=A' B +DA +DC

=A'B + D(A+C)

Can you please explain sir

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@ air1ankit There is only 2 Subcubes of Size 4 ...check it out in K-Map

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AB\CD	00	01	11	10
00	0	0	1	0
01	0	0	1	0
11	0	1	1	0
10	0	1	1	0

No need to consider don't cares, as they will only increase the terms, so make them 0.