Question

Find a counterexample to show that the statement is false. Assume all sets are subsets of a universal set U = {1, 2, 3, 4, 5}. (Enter your answers for A, B, and C in roster notation as a comma-separated list of sets. Enter EMPTY or ∅ for the empty set.)For all sets A, B, and C,A ∪ (B − C) = (A ∪ B) − (A ∪ C).

Answer 1

For subsets A={1,2},B={2,3},C={1,2 5} of U = {1, 2, 3, 4, 5}.

A ∪ (B − C) = (A ∪ B) − (A ∪ C) does not hold.

Step-By-Step Explanation:

U = {1, 2, 3, 4, 5}.

A={1,2}

B={2,3}

C={1,2 5}

For the Left Hand Side

B-C={3}

A ∪ (B − C)= {1,2} ∪ {3} ={1,2,3}

Likewise, the Right Hand Side:

(A ∪ B)={1,2,3}

(A ∪ C)={1,2,5}

(A ∪ B)- (A ∪ C)= {1,2,3}-{1,2,5}={3}

Since, {1,2,3} ≠ {3}, A ∪ (B − C) = (A ∪ B) − (A ∪ C) does not hold.