Question

Prove that for any two set A and B, n(AuB)=n(A)+n(B)-n(AnB)​

Answer 1

Here from vendiagram

n(a-b) =n(a)-n(anb)

And, n(b-a) =n(b)-n(anb)

Again from vendiagram we get 1 formula

n(aub)=n(a-b)+n(b-a)+n(a-b)

n(aub)=n(a)+n(b)-n(anb) [putting the value of n(a-b), n(b-a) ]

Hence proved.

I hope my answer is helpful for you ✌️☺️