How many elements has P(A)

Tuesday, 8 April 2014
How many elements has P(A), if A = Φ?
Φ is an empty or null set so it doesn’t have any element.
So number of element n = 0
Number of elements in a power set n[P(A)] = 2n
plug n = 0 we get n[P(A)] = 20 = 1 used formula [a0 =1]
Hence, P(A) has one element.