Q. Basic Set Union Operation?

Ans.

Suppose instead that your school needs to know which students are taking either art or business or both.

Then the students who are taking either class are in A or in B, or the union of A and B.

The union of two sets A and B, written , is the set of all elements which are in set A or in set B. This can be written as A U B = { x| x ∈ A or x ∈ B }.

The key word in this definition is or. The elements are either in A or B or in both.

Relative Complement

The complement of A relative to B, written B - A, is the set of all elements in B that are not in A. This can be written as B - A = { x| x ∈ A or x ∈ B }.