Question:hard

Which of the following is not same as \((A\Delta B)\cap C\)?

Show Hint

The identity \[ A\Delta B=(A\cup B)\cap(A\cap B)^c \] is extremely useful in simplifying set theory questions.
Updated On: Jun 11, 2026
  • \((A\cap C)\Delta(B\cap C)\)
  • \((A\cap B\cap C)^c\cap((A\cup B)\cap C)\)
  • \(((A\cap B^c)\cap C)\cup((B\cap A^c)\cap C)\)
  • \((A\cap B)^c\cap C\)
Show Solution

The Correct Option is D

Solution and Explanation

Step 1: Write out the symmetric difference.
By definition $A\Delta B=(A\cap B^c)\cup(B\cap A^c)$, the elements in exactly one of $A$ or $B$. We must find which option is NOT equal to $(A\Delta B)\cap C$.
Step 2: Intersect with $C$.
$(A\Delta B)\cap C=((A\cap B^c)\cap C)\cup((B\cap A^c)\cap C)$. This is precisely option (C), so (C) is equal.
Step 3: Check option (A).
$(A\cap C)\Delta(B\cap C)$ keeps the elements of $C$ that lie in exactly one of $A,B$, which is the same set. So (A) is equal.
Step 4: Check option (B).
$(A\cup B)\cap C$ with the part $A\cap B\cap C$ removed keeps elements of $C$ in $A$ or $B$ but not in both, again the symmetric-difference part inside $C$. So (B) is equal.
Step 5: Examine option (D).
$(A\cap B)^c\cap C$ contains every element of $C$ that is merely not in both $A$ and $B$, which includes elements in neither $A$ nor $B$. The symmetric difference excludes those. So (D) is strictly larger.
Step 6: Conclude.
Option (D) is the one that is not the same as $(A\Delta B)\cap C$.
\[ \boxed{(A\cap B)^c\cap C} \]
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