The union of two sets [tex]B[/tex] and [tex]C[/tex], written [tex]B\cup C[/tex], is that set that contains all elements that are members of one (or more) of the sets:
[tex]B\cup C = \{x|x\in B \lor x\in C\}[/tex]
Thus:
[tex]B\cup C =\{a,l,g,e,b,r\}\cup\{m,y,t,h\}=\{x|x\in \{a,l,g,e,b,r\} \lor x\in \{m,y,t,h\}\}={\{a,b,e,g,h,l,m,r,t,y\}[/tex]
