Q.

Let A = {1, 2, 3, ..., 7} and let P(A) denote the power set of A. If the number of functions f:A→P(A) such that a∈f(a), ∀ a∈A is mn, m and n∈N and m is least, then m+n is equal to _____.                [2024]


Ans.

(44)

Given, f:A→P(A)⇒a∈f(a)

It means 'a' will connect with subset which contain element a.

Total options for 1 will be 26(∵ 26 subsets contains 1)

Similarly, for every other element

Now, number of functions from A to P(A) = (26)7=242

i.e., m+n=2+42=44