Question

write the sum of the first n natural numbers​

Answer 1

Answer:

n(n+1)÷2 is the sum of n natural numbers

Answer 2

Answer:

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

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

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

sn=n/2(n+1)

hope it will help u