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Life Group Title

Write each arithmetic series as the sum of terms, find each sum.

  • one year ago
  • one year ago

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  1. Life Group Title
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    |dw:1354173691072:dw|

    • one year ago
  2. Life Group Title
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    this one's different

    • one year ago
  3. Life Group Title
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    how do i find a_1

    • one year ago
  4. Life Group Title
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    is it -5?

    • one year ago
  5. sagarrobo Group Title
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    |dw:1354173877445:dw| put k=10 and get answer

    • one year ago
  6. sagarrobo Group Title
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    answer=1000-275=725

    • one year ago
  7. Life Group Title
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    does a_1 =-5 ?

    • one year ago
  8. geoffb Group Title
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    \(a_1\) is the result of the equation when you plug your first term into it. Your equation is \(100-5k\). The series starts when k = 1, so plug 1 in for k and solve. That's \(a_1\).

    • one year ago
  9. sagarrobo Group Title
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    100-5k is general term for k series so first term=95

    • one year ago
  10. Life Group Title
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    what about a_n, |dw:1354174176642:dw|

    • one year ago
  11. Life Group Title
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    its wrong i know...

    • one year ago
  12. sagarrobo Group Title
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    its wrong refer to my solution above in figure

    • one year ago
  13. geoffb Group Title
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    @Life: You need to distinguish between the formula for the sum of the series and the equation you're given (in this case, 100-5k). You need to find the value for \(a_{10}\), and then plug that into your series summation formula.

    • one year ago
  14. geoffb Group Title
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    \(a_1 = 95\) (you solved that already). \(a_{n} = a_{10} = 100-5(10)\) Plug \(a_{1}\), \(a_{10}\) (which is the *value* you get—*not* 10), and \(n\) into your \(S_{n}\) formula and solve.

    • one year ago
  15. Life Group Title
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    i dont understand how "I" got 95, i never did, but i undetstand everything after that, i thought a1=-5

    • one year ago
  16. geoffb Group Title
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    Your equation is \(100-5k\), so \(a_{1}\) will be the result you get when you plug 1 in for \(k\).

    • one year ago
  17. geoffb Group Title
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    \(a_{2}\) will be the result you get when you plug in 2 for \(k\). \(a_{3}\) will be the result you get when you plug in 3 for \(k\). ... \(a_{10}\) will be the result you get when you plug in 10 for \(k\).

    • one year ago
  18. geoffb Group Title
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    @Life: Have you ever done computer programming? If so, do you know what a for loop is?

    • one year ago
  19. geoffb Group Title
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    That's all a series is. For each value from what's below sigma to what's above it (in this case, between k=1 and k=10), perform the equation. Once you know each one, add them all together.

    • one year ago
  20. Life Group Title
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    my final answer, s10=725, AM I RIGHT? :)

    • one year ago
  21. geoffb Group Title
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    Yes.

    • one year ago
  22. Life Group Title
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    sorry for being dumb lol, i understand it now though, so it was all worth it

    • one year ago
  23. geoffb Group Title
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    You're not being dumb. You are showing effort (not just "what's the answer?"), which is appreciated. :)

    • one year ago
  24. geoffb Group Title
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    Good luck with the rest of them. I have faith that you'll get them all. Good night. :)

    • one year ago
  25. Life Group Title
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    Good night :D

    • one year ago
  26. Life Group Title
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    I really do appreciate you sticking with me until i understood it. It was probably a good half an hour before I finally understood it, so thanks a bunch

    • one year ago
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