Question

if
U = set of natural numbers and A =equals to set of prime numbers
C ' = ? ​

Answer 1

(ii) B = {x: x is a natural number less than 6}

The elements of this set are 1, 2, 3, 4, and 5 only.

Therefore, the given set can be written in roster form as:

B = {1, 2, 3, 4, 5}

(iii) C = {x: x is a two-digit natural number such that the sum of its digits is 8}

The elements of this set are 17, 26, 35, 44, 53, 62, 71, and 80

Answer 2

Answer:

We aren't given about upto what number we should take natural numbers in the set, hence, We take natural numbers and also prime numbers upto 20.

U = {x : x ∈ natural numbers upto 20}

U = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 12, 13, 14, 15, 16, 17, 18, 19, 20}

Now, A = {x : x ∈ prime numbers upto 20}

A = {2, 3, 5, 7, 11, 13, 17, 19}

U is the universal set for set A, also, A ⊂ U.

Then, the Complement : C' of A is the set of all the elements of U which are not the elements of A.

Hence, C' = {1, 4, 6, 8, 9, 10, 12, 14, 15, 16, 18, 20}

Some important terms :

➸ A set is a well defined collection of objects.

➸ Objects and numbers of a set are the same terms given to the elements of the set.

➸ The two methods of representation of sets are roster form and set builder form.

➸ The different types of sets include empty set, finite set, equivalent set, equal set, infinite set and subsets.