ITPEC FE Morning April 2019 Question 23
ITPEC FE Morning April 2019 — Question 23 of 80
Logic circuit simplification — identify the equivalent Boolean expression.
The circuit has two gates feeding into a final OR gate:
- •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 — whenever AND is true, OR is also true
- By absorption: (A AND B) OR (A OR B) = A OR B
Answer: c) A OR B
Why not others:
- (a) A AND B — only represents the top gate, ignores the bottom path
- (b) A AND (A OR B) — simplifies to A by absorption law, not equivalent
- (d) B AND (A OR B) — simplifies to B by absorption law, not equivalent
Key rule: When OR-ing a subset with its superset, the result equals the superset: X OR (X OR Y) = X OR Y.
AI-generated — may contain errors
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