Question

Let C = {1,2,3,4} and D = {1, 2, 3, 4} then which of the following hold not true in this case?

(a) C – D = D – C

(b) C U D = C ∩ D

(c) C ∩ D = C – D

(d) C – D = Φ

This question was posed to me in unit test.

I would like to ask this question from Algebraic Laws on Sets in section Basic Structures: Sets, Functions, Sequences, Sums and Matrices of Discrete Mathematics

Answer 1

Right choice is (c) C ∩ D = C – D

The best I can explain: C ∩ D = {1, 2, 3, 4} ≠ Φ.