Question

SOM yol the series *3*32*3*3*
30. Find the sum of the series (1 + 2) + (1+2+2) + (1+2+2 + 2) + ... upto n terms.​

Answer 1

Answer:

Sn= (n)(2+n) or (n square +2n)

Step-by-step explanation:

If we observe the series carefully... it is an AP

with common difference d=2 and first term = 3

as per the formula for sum of n terms in AP--

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

Sn= (n/2)(2*3+(n-1)2)

Sn= (n/2)(6+2n-2)

Sn= (n/2)(4+2n)

Sn= (n)(2+n) or (n square +2n)