If A and B are two finite sets such that

Question:

If A and B are two finite sets such that n(A) > n(B) and the difference of the number of elements of the power sets of A and B is 96, then n(A) – n(B) = ____________.

Solution:

If n(A) > n(B) and n(P(A)) – n(P(B)) = 96 given 

where $P(A)$ and $P(B)$ represents power left of $A \neq B$ respectively.

Let n(A) = and n(B) = m

i.e n(P(A)) = 2and n(P(B)) = 2m

i.e 2– 2m = 96

2m(2–m – 1) = 96 = 2× 3

i.e 2m = 25

i.e m = 5 and 2–m – 1 = 3

2–m  = 4 = 22

i.e. n – = 2

i.e = 2 + m

n = 2 + 5

i.e. = 7

∴ n(A) – n(B) = – = 2

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