Union
The union between two sets $A$ and $B$ is a set that contains all the elements that are in $A$ or in $B$. The union of sets $A$ and $B$ is denoted as $A \cup B = \{x | x \in A \text{ or } x \in B\}$.
The union between two sets $A$ and $B$ is a set that contains all the elements that are in $A$ or in $B$. The union of sets $A$ and $B$ is denoted as $A \cup B = \{x | x \in A \text{ or } x \in B\}$.