Union of sets / Addition of sets / A or B / Either A or B / At-least one of A or B

 Union of sets 

1) Union meaning

2) Representation of union of n sets in symbol form:

** Here big U represents union of Ai sets, and Ai represents variables , where the value of i  starts from , i=1  and ends at n. Therefore the union of Ai will contain elements [A1 , An] , this is a closed interval meaning A1 and An are included

3) Venn-diagram representation of Union of sets:

** the entire shaded area is A union B

4) Union of three sets (** in the picture U set is universal set)

5) Some Properties of Union of sets:

6) Some NCERT sums: