Question

Roster form of the following set is : A={x: x ∈ 3N and N<5}
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Answer 1

Answer:

x=3n

where n is a natural number and n<8

So, n can be any digit from 1,2,3,4,5,6,7

So, in roster form

A={3,6,9,12,15,18,21}

Cardinal number = no. of distinct elements in the Set=7

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