Difficulty: Easy
Correct Answer: A + B = B + A
Explanation:
Introduction / Context:Boolean algebra underpins digital logic design. Several fundamental identities are frequently tested: commutative, associative, distributive, and idempotent laws. This question focuses on identifying the commutative law, which states that operands may be exchanged without affecting the result.
Given Data / Assumptions:
Concept / Approach:The commutative laws are: A + B = B + A and A * B = B * A. They specifically show that the order of operands does not matter for OR or AND. Other identities (associative, distributive, idempotent) express different properties and should not be confused with commutativity.
Step-by-Step Solution:
Review each option and classify its identity type. Identify the statement that swaps operand order without changing the result. Select A + B = B + A as the commutative law for OR.Verification / Alternative check:Test with values: let A=0, B=1. A + B = 1 and B + A = 1, therefore the equality holds and demonstrates operand order irrelevance.
Why Other Options Are Wrong:
A * (B + C) = A*B + A*C: distributive law, not commutative. (A + B) + C = A + (B + C): associative law for OR. A + A = A: idempotent law for OR. None: incorrect because a correct commutative statement is present.Common Pitfalls:Confusing distributive with commutative due to similar symbol patterns, and overlooking that commutativity solely concerns swapping operands, not grouping or distribution.
Final Answer:A + B = B + A
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