Quantcast

A community for students. Sign up today!

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

infinitemoes

  • one year ago

Please help! What is the sum of the series? 20 on top and n-1 on the bottom of ∑(5-n)

  • This Question is Closed
  1. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    did you mean n=1?

  2. Dido525
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 0

    @infinitemoes

  3. infinitemoes
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    no it's a n-1 on the bottom of the sigma.

  4. mrbarry
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    \[\sum_{n-1}^{20} (5-n)\]

  5. infinitemoes
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes exactly like that

  6. mrbarry
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    It should be n=1 I am certain. If we did this "manually" we would have 4 + 3 + 2 + ... Right?

  7. infinitemoes
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    alright..

  8. mrbarry
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    This is an arithmetic sequence b/c we are adding -1 over and over. There is a formula to solve this, Arithmetic Series Formula. Do you know it?

  9. infinitemoes
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I think I got the answer. -110

  10. mrbarry
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Let's see. The formula says: 1/2 the number of items times (first term + last term) 1/2 (20) (4 + -15) 10 (-11) Good job.

  11. infinitemoes
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    thank you! :)

  12. mrbarry
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    You are welcome. All done? Thanks for the medal.

  13. infinitemoes
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Well I do have a couple more questions, but I'm gonna post them separate to this post.

  14. mrbarry
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    Of course.

  15. Not the answer you are looking for?
    Search for more explanations.

    • Attachments:

Ask your own question

Ask a Question
Find more explanations on OpenStudy

Your question is ready. Sign up for free to start getting answers.

spraguer (Moderator)
5 → View Detailed Profile

is replying to Can someone tell me what button the professor is hitting...

23

  • Teamwork 19 Teammate
  • Problem Solving 19 Hero
  • You have blocked this person.
  • ✔ You're a fan Checking fan status...

Thanks for being so helpful in mathematics. If you are getting quality help, make sure you spread the word about OpenStudy.

This is the testimonial you wrote.
You haven't written a testimonial for Owlfred.