LEARN MATH STEP BY STEP THROUGH VERY EASY PROCESS

DEFINATION & FORMATION OF SETS

__SETS -__

**A set is a well-defined collection of objects. By ‘well defined’ we mean that it must be
possible to tell beyond doubt whether or not a given object belongs to the
collection that we are considering.**

**For example, the following are well defined collections and
so are example of sets**

**(i) The set of numbers 1, 3, 5, 7, and 10.**

**(ii) The set of students of your drawing class**

**The following does not describe a well-defined collection
and so are not sets –**

**(i) The vegetables which taste good to all. People may have
different tastes.**

**(ii) All good movies. People may have different likings.**

**Members of a set and symbol for ‘Belongs To’ –**

**The objects that belong to a set are called members of elements of the set. The
Greek letter ‘epsilon’ ∈ is used
for understanding ‘belongs to’.**

**For Example –**

**a ∈ {a, b, c},
**

**b ∈ {a, b, c}, **

**c ∈ {a, b, c},**

**we also say that, ‘a’, ‘b’, ‘c’
are included in the set.**

**The symbol ∉ is used to mean ‘is not a member of’.**

**Thus 1 ∉ {0, 2, 4, 6}**

__Note –__ The braces { } are used
to enclose the members of a set

**Representation of a Set –**

**Capital letters, e.g., A, B, S
etc., used to name sets. There are three ways of representing a set.**

**(1) In words:- We can use words
to describe a set, e.g., the set of multiples of whole numbers less than 10.**

**(2) Roster or Tabulation
Method,**

**(3) Rule Method or Set Builder
Method,**