Question

What is the sum of first
neven natural numbers?​

Answer 1

Answer:

n[n+1]

Step-by-step explanation:

Sn= 2+4+6+8+.....

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

= n/2 [2×2 + (n-1)2]

= n[ 2+ n-1]

= n[n+1]

Answer 2

S = n2[(a + l)]

solution:-

We will discuss here how to find the sum of first n natural numbers.

Let S be the required sum.

Therefore, S = 1 + 2 + 3 + 4 + 5 + .................... + n

Clearly, it is an Arithmetic Progression whose first term = 1, last term = n and number of terms = n.

Therefore, S = n2(n + 1), [Using the formula S = n2(a + l)]