If number of elements in set is 0, it is an empty set.

It is also called null set or void set.

 

Example:

A = {x: x is a natural number less than 1}

Since, natural number = 1, 2, 3, 4, …

There is no natural number less than 1

Hence,

A = {}

or A is an empty set.

We can also write

A = ∅


B = {x: x 2 = 4, x is an odd number}

x 2 = 4

x  = ± √4

x = ± 2

So, x = -2, 2

Since, x is even, it means set B is empty

B = {} = ∅

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Davneet Singh

Davneet Singh has done his B.Tech from Indian Institute of Technology, Kanpur. He has been teaching from the past 13 years. He provides courses for Maths, Science, Social Science, Physics, Chemistry, Computer Science at Teachoo.