=
{ 1,2,3}
B
=
{3,4}
AUB stands for the union of set a and set b, which is to put the contents of a and b together in layman's terms. The mathematical expression is:
Aubu
=
{ 1,2,3,4}
Be careful not to write AUB.
=
{ 1,2,3,3,4}
Write only once. Repeat.
|AUB| indicates the number of elements in the set AUB, that is, 4.
|A|
=
4,
|B|
=
3.