Question

In which of the following sets A – B is equal to B – A?

(a) A = {1, 2, 3}, B = {2, 3, 4}

(b) A = {1, 2, 3}, B = {1, 2, 3, 4}

(c) A = {1, 2, 3}, B = {2, 3, 1}

(d) A = {1, 2, 3, 4, 5, 6}, B = {2, 3, 4, 5, 1}

I have been asked this question in class test.

My question is taken from Set Operations in chapter Basic Structures: Sets, Functions, Sequences, Sums and Matrices of Discrete Mathematics

Answer 1

The correct option is (c) A = {1, 2, 3}, B = {2, 3, 1}

Best explanation: A- B= B-A = Empty set.