Question

If A and B are two disjoint sets, then prove that n(AUB) = n(A) + n(B)​

Answer 1

Step-by-step explanation:

its simple

disjoint means nothing common

so their intersection will b zero

so n(AuB)=n(A)+n(B)-n(A intesection B)

=n(A)+n(B)

Answer 2

Proof:

Known:

   n(A∪B) = n(A) + n(B) - n(A∩B)

Given,

A and B are disjoint i.e

   n(A∩B) = 0

So,

n(A∪B) = n(A) + n(B) - n(A∩B)

=>  n(A∪B) = n(A) + n(B) - 0

Hence,

n(A∪B) = n(A) + n(B)

proved.