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Find the sum of an arithmetic series

Year 12 maths · Fieldbook Learning

Name ______________________ Date __________

Add the first and last term, multiply by the number of terms, and halve it.

  1. Find the sum of the first 7 terms of the arithmetic sequence −5, −2, 1, …
  2. Find the sum of the first 10 terms of the arithmetic sequence −14, −11, −8, …
  3. Find the sum of the first 7 terms of the arithmetic sequence −15, −6, 3, …
  4. Find the sum of the first 10 terms of the arithmetic sequence −3, 1, 5, …
  5. Find the sum of the first 10 terms of the arithmetic sequence 6, −1, −8, …
  6. Find the sum of the first 8 terms of the arithmetic sequence 7, 11, 15, …
  7. Find the sum of the first 6 terms of the arithmetic sequence −14, −15, −16, …
  8. Find the sum of the first 6 terms of the arithmetic sequence 13, 12, 11, …
  9. Find the sum of the first 10 terms of the arithmetic sequence −3, −6, −9, …
  10. Find the sum of the first 17 terms of the arithmetic sequence 7, 15, 23, …
  11. Find the sum of the first 18 terms of the arithmetic sequence 9, 11, 13, …
  12. Find the sum of the first 11 terms of the arithmetic sequence 3, 10, 17, …
  13. Find the sum of the first 21 terms of the arithmetic sequence 5, 4, 3, …
  14. Find the sum of the first 11 terms of the arithmetic sequence −9, −1, 7, …
  15. Find the sum of the first 20 terms of the arithmetic sequence 10, 1, −8, …
  16. Find the sum of the first 21 terms of the arithmetic sequence −5, −7, −9, …
  17. Find the sum of the first 38 terms of the arithmetic sequence −5, −7, −9, …
  18. Find the sum of the first 24 terms of the arithmetic sequence 6, 11, 16, …
  19. Find the sum of the first 29 terms of the arithmetic sequence 1, −6, −13, …
  20. Find the sum of the first 31 terms of the arithmetic sequence −1, −2, −3, …
More free practice: fieldbooklearning.com/uk/practice/year-12/arithmetic-series-sum/

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Answer key: Find the sum of an arithmetic series

  1. 28
  2. -5
  3. 84
  4. 150
  5. -255
  6. 168
  7. -99
  8. 63
  9. -165
  10. 1207
  11. 468
  12. 418
  13. -105
  14. 341
  15. -1510
  16. -525
  17. -1596
  18. 1524
  19. -2813
  20. -496