A Set is commonly defined as an assembly of items, recognized as foundations. These items could be any possible thing, including digits, alphabets, colors etc. However, none of the items of the set can be a set in itself.

Presentation of sets:

We mark sets using brackets and signify them with capital letters. The most standard technique to define sets is by enlisting all its items.
For example:
P= {5, 6, 7, 8, 9, 10…….18} is the set of counting numbers beginning from 5.
Q= {Black, white, Red, Yellow…} is a set of colors.
R= {-3, -2, -1, ., 1, 2, 3….} is a set of all integers.

Formula or Rule for Set Theory

The set that consists of all the elements of a specified group is called the universal set and is denoted by the symbol ‘µ,’ also known as ‘mu.’
For two sets P and Q,
n(PᴜQ) is the number of items existent in either of the sets P or Q.
n(P∩Q) is the number of items existent in both the sets P and Q.
n(PᴜQ) = n(P) + (n(Q) – n(P∩Q)
For three sets P, Q and R,
n(PᴜQᴜR) = n(P) + n(B) + n(R) – n(P∩Q) – n(Q∩R) – n(R∩P) + n(P∩Q∩R)

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