Question

Find cardinality of set B

B = {∅, {1}, {1, 2}, {1, 2,3}, · · · , {1, 2, · · · , m}}

Answer 1

m + 1

Explanation:

Given set,

B = {∅, {1}, {1, 2}, {1, 2,3}, · · · , {1, 2, · · · , m}},

Since, the elements of S are,

{} , {1}, {1, 2}, {1, 2, 3}....... {1, 2,.....m }

Thus, every next set contains one more succeeding natural number than the previous set.

So, if the last set contains m natural numbers.

Then there are 'm + 1' sets in B ( m sets included ∅ )

Hence, the number of elements in B is 'm+1'

I.e. Cardinality of B is m + 1.