Set difference A − B with small numeric sets: Let A = {1, 2, 3, 4, 5} and B = {2, 4, 6}. Find A − B (elements in A that are not in B).

Difficulty: Easy

Correct Answer: {1, 3, 5}

Explanation:

Introduction / Context:Set difference A − B collects items that belong to A but not to B. It is a fundamental operation in set theory and appears frequently in data filtering and logic puzzles.

Given Data / Assumptions:

  • A = {1, 2, 3, 4, 5}
  • B = {2, 4, 6}

Concept / Approach:Remove from A every element that appears in B. Elements 2 and 4 are common and are excluded from A − B.

Step-by-Step Solution:Start with A: {1, 2, 3, 4, 5}Remove 2 and 4 (present in B)Result: {1, 3, 5}

Verification / Alternative check:Symmetric difference would include 2 and 4 differently, but set difference strictly excludes A’s elements present in B.

Why Other Options Are Wrong:{2, 3, 5} and {1, 4, 5} keep elements that should be removed; {2, 3, 6} includes 6, which is not in A.

Common Pitfalls:Confusing A − B with B − A or with symmetric difference.

Final Answer:{1, 3, 5}

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