Question

If A = {1, 2, 3}, B = {2, 3, 4}, then the set difference A\B is:

• A. $\{1, 2, 3\}$
• B. $\{2, 3, 4\}$
• C. $\{4\}$
• D. $\{1\}$

Answer 1

Answer:

$\{1\}$

The correct answer is Option D: {1}.

In set theory, the set difference $A \setminus B$ (also written as $A - B$) basically means "take everything in set $A$ and remove anything that also appears in set $B$."

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Step-by-Step Breakdown

1. Identify Set A: $\{1, 2, 3\}$

2. Identify Set B: $\{2, 3, 4\}$

3. Find the common elements: Both sets share the numbers 2 and 3.

4. Perform the subtraction: Remove those shared numbers from Set A.

   • Original A: $\{1, \mathbf{2, 3}\}$

   • A - B =$\{1\}$