Question

State which of the following sets are finite or infinite.
(i) {x : x ∈ N and (x − 1) (x − 2) = 0} (ii) {x : x ∈ N and x2 = 4}
(iii) {x : x ∈ N and 2x − 2 = 0} (iv) {x : x ∈ N and x is prime}
(v) {x : x ∈ N and x is odd}

Answer 1

Finite Sets:  A set in which one can principly count and finish the counting.

Infinite Sets: A set which is not finite is called infinite.

(i) {x : x ∈ N and (x − 1) (x − 2) = 0}

Hence, {1,2}

So,finite

(ii) {x : x ∈ N and x2 = 4}

2x=4

x=2

{2}

So,finite

(iii) {x : x ∈ N and 2x − 2 = 0} (iv) {x : x ∈ N and x is prime}

{2,3,5,7,11,13,17,.....................}

Can't finish counting

Hence, Infinite

(v) {x : x ∈ N and x is odd}

{1,3,5,7,9,11,..............}

Hence, Infinite.

Answer 2

Answer:

State which of the following sets are finite or infinite.

(i) {x : x ∈ N and (x − 1) (x − 2) = 0}

(ii) {x : x ∈ N and x2 = 4}

(iii) {x : x ∈ N and 2x − 2 = 0}

(iv) {x : x ∈ N and x is prime}

(v) {x : x ∈ N and x is odd}