Q. 525.0( 1 Vote )

# Mark the correct alternative in each of the following:

Let A = {1, 2, …, n} and B = {a, b}. Then the number of subjections from A into B is

A. ^{n}P_{2}

B. 2^{n} – 2

C. 0

D. none of these

Answer :

Given that A = {1, 2, …, n} and B = {a, b}

The number of functions from a set with n number of elements into a set of 2 number of elements = 2^{n}

But two functions can be many-one into functions.

Hence, answer is 2^{n} – 2.

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