Sets and Functions
 A set is a welldefined collection of objects.
 Sets are usually represented by capital letters A, B, C, D, X, Y, Z, etc. The objects inside a set are called elements or members of a set. They are denoted by small letters a, b, c, d, x, y, z, etc.
 If a is an element of a set A, then we say that “a belongs to A” and mathematically we write it as “a∈A”; if b is not an element of A, then we write “b∉A”.
 There are three different ways of representing a set:
 Description method: Description about the set is made and it is enclosed in curly brackets { }.
For example, the set of composite numbers less than 30 is written as follows:
{Composite numbers less than 30}

 Roster method or tabular form: Elements are separated by commas and enclosed within the curly brackets { }.
For example, a set of all integers greater than 5 and less than 9 will be represented in roster form as {6, 7, 8}.

 Setbuilder form or rule method: All the elements of the set have a single common property that is exclusive to the elements of the set i.e., no other element outside the set has that property.
For example, a set L of all integers greater than 5 and less than 9 in setbuilder form can be represented as follows:
L = {x : x is an integer greater than 5 and less than 9}
 Some important points:
 The order of listing the elements in a set can be changed.
 If one or more elements in a set are repeated then the set remains the same.
 Each element of the set is listed once and only once.
 On the basis of number of elements, sets can be classified as:
 Finite set − A set that contains limited (countable) number of different elements is called…
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