Let X and Y be sets:
X = \{A\}Y = \{B\}
\{ \}
What is the set X \cup Y?
Remember that \cup refers to the union of sets.
The union of two sets X and Y is the collection of elements which are in X or in Y or in both X and Y.
The members of a set must be unique, and the order doesn't matter.
X \cup Y = \{ANSWER\}
What is the set X \setminus Y?
Remember that \backslash refers to the difference between sets.
The difference of two sets X and Y is the collection of elements which are in X but not in Y.
The members of a set must be unique, and the order doesn't matter.
X \setminus Y = \{ANSWER\}
What is the set X \cap Y?
Remember that \cap refers to the intersection of sets.
The intersection of two sets X and Y is the collection of elements which are in X and also in Y.
The members of a set must be unique, and the order doesn't matter.
X \cap Y = \{ANSWER\}