can i get the derivation of the formula n(n+1)/2

Asked by dhruvisha sagothia | 3rd Oct, 2013, 01:08: PM

Expert Answer:

Sum of first n natural numbers = n(n+1)/2
 
Derivation:
S = 1 + 2 + 3 + ... + n
S = n + (n-1) + ... + 2 + 1
 
Adding column wise, we get,
2S = (n+1) + (n+1) + (n+1) + ... ... + (n+1)          (n times)
2S = n(n+1)
S = n(n+1) / 2

Answered by  | 3rd Oct, 2013, 01:50: PM

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