Unit 12 Answers
1. x A = {(x, y) | x and y A} = = {(x, y)| x A and y } = A x
2. mn
3.
4.
a) B A. For since A B = A every element of B is also in A . But A may have more elements than B .
b) A B = . For A - B = A means that subtracting elements of B does not change A. Hence no elements of B are in A. Hence A and B have no elements in common.
5. A B x (x A x B ) x (x B x A) x(x x )