Answer:

The union of A and B is the set of all those elements which belong either to A or to B or both A and B. Now we will use the notation A U B (which is read as 'A union B') to denote the union of set A and set B. Thus, A U B = {x : x ∈ A or x ∈ B}. Therefore, the shaded portion in the adjoining figure represents A U B