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 = {} = ∅

  1. Chapter 1 Class 11 Sets
  2. Concept wise
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Davneet Singh
Davneet Singh is a graduate from Indian Institute of Technology, Kanpur. He has been teaching from the past 8 years. He provides courses for Maths and Science at Teachoo. You can check his NCERT Solutions from Class 6 to 12.