Question

What is the sum of the first 'n' natural number?​

Answer 1

First n natural numbers are in ap.

so , a will be 1

d will be 1

then sum of first n natural no. =

Sn = n/2(2a+(n-1)d)

= n/2(2(1)+(n-1)1)

=n/2(2+n-1)

=n/2(n+1)

=n²+n/2