Question

If `Aa n dB` are two sets having 3 elements in common. If `n(A)=5,n(B)=4,` find `n(AxxB)a n dn[(AxxB)nn(BxxA)]dot`

Answer 1

Let
`A=(a,b,c,d,e}`
`B={a,b,c,p}`
1)`n(A*B)=5*4=20`
2)`A*B={(a,a),(a,b),(a,c),(b,a),(b,b),(b,c)}`
`B*A={(a,a),(a,b),(a,c),(b,a),(b,b),(b,c)}`
`=(n(A*B) nn(B*A))=9`.