x
A = {(x, y) | x 
and y
A} =
=
{(x, y)| x
A and y
} =
A x
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
)