# Different Notations in Sets

What

are the different notations in sets?

To learn about sets we shall use some accepted notations
for the familiar sets of numbers.

Some of the different notations used in sets are:

 ∈∉: or |∅n(A)∪∩NWI or ZZ+Q Q+RR+C Belongs to  Does not belongs to  Such thatNull set or empty setCardinal number of the set AUnion of two setsIntersection of two setsSet of natural numbers = {1, 2, 3, ……}Set of whole numbers = {0, 1, 2, 3, ………}Set of integers = {………, -2, -1, 0, 1, 2, ………}Set of all positive integersSet of all rational numbersSet of all positive rational numbersSet of all real numbersSet of all positive real numbersSet of all complex numbers

These
are the different notations in sets generally required while solving various
types of problems on sets.

Note:

(i) The
pair of curly braces {  } denotes a set.
The elements of set are written inside a pair of curly braces separated by
commas.

(ii) The
set is always represented by a capital letter such as; A, B, C, …….. .

(iii) If
the elements of the sets are alphabets then these elements are written in small
letters.

(iv) The
elements of a set may be written in any order.

(v) The
elements of a set must not be repeated.

(vi) The Greek letter Epsilon ‘∈’ is used for the
words ‘belongs to’, ‘is an element of’, etc.

Therefore, x ∈ A will be read as ‘x belongs to set A’ or ‘x is
an element of the set A’.

(vii) The symbol ‘∉’ stands for ‘does not belongs to’
also for ‘is not an element of’.

Therefore, x ∉ A will read as ‘x does not
belongs to set A’ or ‘x is not an element of the set A’.

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