If A={1,2,3...} and N is the set of natural numbers, then check whether A and N are equal?

Median of 1st n natural numbers is

variance of 1st n natural number is

If X = { 4^n-3n-1: n in N} and Y = { 9(n-1):n in N } where N is the set of natural numbers then X cup Y is equal to

Let S = {(a,b,c) in N xx N xx N : a+b+c=21, a le ble c} and T = {(a,b,c) in N xx N xx N : a,b,c are in A.P} where N is the set of all natural numbers . Then the numbers of elements in the set S cap T is

If X={4^n-3n-1:n in NN}andY={9(n-1):n in NN} where NN is the set of natural numbers, then X cupY is equal to__

The mean of square of 1st n natural number is

If NN be the set natural numbers, then prove that, the mapping f: NN rarr NN defined by , f(n) =n-(-1)^(n) is a bijection.

The sum of the cubes of 1st n natural numbers is

If the mean of the first n odd natural numbers be numbers itself, then n is

If aN={ax:x in N(natural number)} then 3N cap 7N is equal to