Question

What is the sum of the terms of the series 4+7+10+.....+22?

Answer 1

The sum is `91`

Explanation:

It is the sum of an arithmetic progression (series) with first term

`a_1=4` and ratio `r=3`

The sum is

`S_7=7/2*(a_1+a_7)=7/2*(4+22)=7*13=91`