Formula used:
The union of two sets.
Let A and B be two sets. The union of A and B can be written in set notation as A∪B
A∪B={x|x∈A or x∈B}
Let L and L' be the languages defined on a particular alphabet.
L is a set of particular string defined on the alphabet.
L' is the set which contains all the strings that does not belong to L