Question

If A = {1,20,30..} and B = {4,6} find n(A-B)?​

Answer 1

Explanation:-

Given sets are A = { 1,20,30}

B = { 4,6}

Now,

A-B = { 1,20,30} -{ 4,6}

⇛ A-B = { }

Since there are no common elements in both A and B sets

⇛Number of elements in A-B = 0

⇛n(A-B) = 0

Therefore, n(A-B) = 0

ADDITIONAL COMMENT:

Points to know:-

Empty set :-

• A set having no element is called an empty set or void set or null set .It is denoted by phi or { }
• The cardinal number of the Null set = 0

Difference of two sets :-

• A and B are two sets ,The set of elements which belongs to A and does not belong to B is called The difference between the two sets A and B and it is denoted by A-B.

Cardinal number of a set :-

• The number of all distinct elements in a set is called its Cardinal number .
• It is denoted by n(A).

Answer 2

Answer:

If A = {1,20,30..} and B = {4,6} find n(A-B)?