ITPEC FE Morning October 2021 Question 21
ITPEC FE Morning October 2021 — Question 21 of 80
Logic circuit simplification — OR gate absorbs AND of the same inputs.
The circuit has three gates:
- •Top gate: AND →
A AND B - •Bottom gate: OR →
A OR B - •Final gate: OR →
(A AND B) OR (A OR B)
Simplification:
- A AND B is a subset of A OR B
- Therefore (A AND B) OR (A OR B) = A OR B
Why not others:
- (a) A AND B — false when only one input is true; circuit outputs true
- (b) A AND (A OR B) — simplifies to just A (absorption law)
- (d) B AND (A OR B) — simplifies to just B (absorption law)
Key rule: Absorption law: X OR (X AND Y) = X. When OR absorbs AND of the same variables, only OR remains.
AI-generated — may contain errors
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