Question

let a = {x:x is positive integral multiple of 3 less than 31}and b = {x:x is prime number less than 30} ,then n ( aub) +n(aub) is equal to :​

Answer 1

Answer:

integral multiples of three less than 31 are 3,6,9,12,....30

prime no less than 30:2,3,5,7,11,13,17,23,29

N(aUB)=10+9=19 since bo of elements in a are 10 and in b are 9

so now n (a intersection b)= all common elements in a and b i.e. 3 (1 element)

so an (aUB) +n(anb)=19+1=20

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