Question

for the arithmetic sequence beginning with the terms {5, 6, 7, 8, 9, 10...}, what is the sum of the first 17 terms? 187 243 221 200 save

Answer 1

221

Explanation:

5 is the first term, then:

5 + 16 = 21

22 is the last term

5 + 21 = 26

6 + 20 = 26

7 + 19 = 26

.....

.....

12 + 14 = 26

and

13

There are 8 sum of 26 each and 13

Then:

8*26 + 13 = 221