Question

3.The sum of first n natural number is………​

Answer 1

Answer:

Sum of first n natural numbers=2n(n+1)

Answer 2

Answer:

Explanation:

S  

n

​

=1+2+3+....+n

S  

n

​

=  

2

n

​

[2a+(n−1)d] where a=1,d=2−1=1

⇒S  

n

​

=  

2

n

​

[2×1+(n−1)1]

⇒S  

n

​

=  

2

n

​

(n+1)

∴ Sum of first n natural numbers=  

2