Question

If A={1, 3,5,7}={2, 4,6}then, find n(AUB) ​

Answer 1

Answer:

n(A∪B)=n(A)+n(B)−n(A∩B)−−−−−−−(1)

Given n(A)=7

n(B)=9

n(A∪B)=14

Substituting in 1

14=7+9−n(A∩B)

⇒n(A∩B)=16−14=2

Answer 2

Answer:

In set theory, if A and B are sets, then the union of A and B , written A ⋃ B, is {x: x ∈ A or x ∈ B}. By asserting that x ∈ A or x ∈ B, we do not exclude the possibility that x is a member of both A and B. Further, if the same object/element is member of both A and B, then that element is counted only once in the new set formed by the union of A and B.

Given, A = {1,2,3,4} and B = {1,5,7}.

∴ By definition, A ⋃ B = {1,2,3,4,5,7}