Find the sum the first 25th terms of following series:

2,5,8,11,14,⋯

Formula to find nth term:

Formula to find sum of n terms:

### Solution

# First find the 40 th term: a40 = a1+(n−1)d = 2+39(3) = 119 # Then find the sum: Sn = n(a1+an)/2 = 40(2+119)/ 2 = 2420