If `n>=2` then the number of surjections that can be defined from {1 2 3......n} onto {1 2} is

If A={1,2,3,.....n],nge2 and B={a,b} , then the number of surjections from A to B is

Find the number of all onto functions from the set A={1,\ 2,\ 3,\ ,\ n} to itself.

Find the number of all onto functions from the set A={1,\ 2,\ 3,\ ,\ n} to itself.

Number of ways in which three numbers in A.P. can be selected from 1,2,3,..., n is a. ((n-1)/2)^2 if n is even b. n(n-2)/4 if n is even c. (n-1)^2/4 if n is odd d. none of these

Given that n is odd, number of ways in which three numbers in AP can be selected from 1, 2, 3,……., n, is

If m=number of distinct rational numbers p/q in (0,1) such that p, q in {1,2,3,4,5} and n= number of onto mappings from {1, 2, 3} onto {1,2}, then m-n is

The number of all onto functions from the set {1,2,3,4,….,n} to itself is

Show that the number of ways in which three numbers in arithmetical progresssion can be selected from 1,2,3,……..n is 1/4(n-1)^(2) or 1/4n(n-2) according as n is odd or even.

Let A = {1, 2, 3, ..., n} and B= {a,b}. Then the number of surjections from A into B is

Let A = {1,2,3,…,n} and B = {x,y}. Then the number of surjections from B into A is