A community for students.

Here's the question you clicked on:

55 members online
  • 0 replying
  • 0 viewing

Babynini

  • one year ago

A partial sum of an arithmetic sequence is given. Find the sum. 1+5+9+...+401

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

    a=1, d=4 Sn=(n/2)(a1+a2) I'm not sure how to plug in these numbers though!

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

    @jim_thompson5910 :) do you have time?

  3. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    it should be Sn = (n/2)(a1 + an)

  4. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    an = a1 + d(n-1)

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

    right right.

  6. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    First you need to find n

  7. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    an = a1 + d(n-1) 401 = 1 + 4(n-1) n = ??

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

    101 ?

  9. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    yes

  10. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    a1 = 1 an = 401 n = 101 Sn = (n/2)*(a1 + an)

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

    er so sn=20301

  12. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    I got the same

  13. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    wolfram agrees http://www.wolframalpha.com/input/?i=1%2B5%2B9%2B...%2B401

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

    haha yay! the wolfram stamp of approval x) thanks so much.

  15. jim_thompson5910
    • one year ago
    Best Response
    You've already chosen the best response.
    Medals 1

    np

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

    • Attachments:

Ask your own question

Sign Up
Find more explanations on OpenStudy
Privacy Policy

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.