Arithmetic Sequence / Series

-3

An arithmetic sequence has a fifth term of 30 and the twentieth term of -15. Find the common difference

915

An arithmetic sequence has first term 12, and the third term is 26. Find the sum of the first 15 terms.

70

Find arithmetic series from the 3rd to 9th terms, given the 3rd term is 1 and the 9th term is 19

-30

Find the 12th term in a sequence with common difference -8 and first term 58.

96

Find the 21st term in the sequence. -4, 1, 6, 11, 16, ...

279

Find the 72nd term in the sequence: -5, -1, 3, 7, ..

298

Find the 75th term of the sequence with first term 2 and common difference 4

-7

Find the common difference in the sequence: 10, 3, -4, -11, ...

9

Find the common difference: 16, 25, 34, ..

17

Find the first term in a sequence where the common difference is 6 and the eleventh term is 77.

375

Find the nth partial sum of the sequence 75, 70, 65, 60, ... , where n = 25

155

Find the sum of the first 10 terms of the sequence 2, 5, 8, 11, ...

-37

Given the arithmetic sequence an = -2n-25, find the 6th term.

40

How many terms are there in the sequence: 5, 10, 15, ... ,195, 200

-4

If the 7th term of an arithmetic sequence is 2 and the 13th term is 8, what is the first term?