Mathematics

The sum of the first n positive integers is

The sum of the first n positive integers is

  • A.1/2 n(n-1)
  • B.
    n(n+1)
  • C.
    n(n-1)
  • D.1/2 n(n+1)
Correct Answer: Option D
Explanation

Let the positive integers be 1, 2, ,3, 4, …..n
∴ a = 1, d = 1 and n = n
Sn = n/2(2a + (n-1)d)
= n/2 (2 + n – 1)
= 1/2n(n + 1)