Question

what is the sum of first n natural numbess?​

Answer 1

Answer:

Here a = 1, d = 1. Hence option (4) is the answer.

Answer 2

Answer:

The sum of the first n natural number = 1+2+3+…n

Here a = 1, d = 1.

Sum of AP = (n/2)(2a+(n-1)d)

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

= (n/2)(n+1)

= n(n+1)/2

Hence option (4) is the answer.