Question

Print sum of following series : 2 _ 5 + 10 _ 17 + 26 . . . . . . . . . n terms 101 100 98 95 90​

Answer 1

Answer:

Find the sum of the first 40 terms of the arithmetic sequence

2,5,8,11,14,⋯

First find the 40 th term:

a40=a1+(n−1)d        =2+39(3)=119

Then find the sum:

Sn=n(a1+an)2S40=40(2 + 119)2=2420