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GATE 2016 EE (EE2) – Question 36

Analog and Digital Electronics · VCOs and timers, combinatorial and sequential logic circuits, multiplexers, demultiplexers · 2 marks · Multiple choice

The Boolean expression $\overline{(a+\bar b+c+\bar d)+(b+\bar c)}$ simplifies to

  1. $1$
  2. $\overline{ab}$
  3. $ab$
  4. $0$

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Correct answer: (D) $0$

Explanation

The sum inside the outer complement includes both b and its complement b̄. Therefore its value is one for every input, by b+b̄=1.

It also includes c+c̄=1, providing the same conclusion independently. Complementing that constant one yields **0, D**.

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