Question

How many elements has P(A), if A = Φ?

Answer 1

It is known that if A is a set with p elements, that is, n( A )=p, then,

n[ P( A ) ]= 2 p

It is given that A=ϕ, then, n( A )=0.

So,

n[ P( A ) ]= 2 0 =1

Therefore, there is one element in P( A ).