1. Not finding help here? Sign up for a free 30min tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Summand part in summation notation

  1. Mar 4, 2005 #1
    I need to write the following series in summation notation

    1) 1+3+5+7+9+11 SUMMAND (2k-1)? is this right?

    2) 4+6+8+10+12+12+16+18 (2k+2)? is this right?

    Have I got it?
     
    Last edited: Mar 4, 2005
  2. jcsd
  3. Mar 4, 2005 #2

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Okay.What does these symbols mean
    [tex] \sum_{k=1}^{n} k [/tex] ?

    Daniel.
     
  4. Mar 4, 2005 #3
    [tex] \sum_{k=1}^{n} k [/tex]

    ok the n= the last number in the series

    k=1 the one is the first number in the series

    k is the summand its used to get the terms in the series u input number k through n to get the series
     
  5. Mar 4, 2005 #4
    ok for the first series i posted i got the summand to be (2k-1) with a 6 over the sigma and for the second series I got (2k+2) as the summand with 18 over the sigma, is this correct?
     
  6. Mar 4, 2005 #5

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Perfect,then u agree it means just:1+2+...+k+...+n ...?

    Okay.Now imagine how would your first sum would look like...You already did...Great.

    [tex] \sum_{k=0}^{5} (2k+1) [/tex]

    Agree...?

    Daniel.

    P.S.For some reason,we prefer the "+" for the general form of an odd #.
     
  7. Mar 4, 2005 #6

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Nope,not really.U see,the last term must coincide with the value of the general term when evaluated with the superior value:
    [tex] \sum_{k=0}^{5} (2k+1)=...+11 [/tex]

    [tex] 11=(2k+1)|_{k=5} [/tex]...

    Okay...?

    Daniel.
     
  8. Mar 4, 2005 #7
    [tex] \sum_{k=0}^{5} (2k+1) [/tex]

    ok so this is the only answer for the first series?

    [tex]\sum_{k=4}^{18} (2k+2) [/tex] and is this answer correct for the second series?
     
  9. Mar 4, 2005 #8

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    Okay,true.Have your way,it's basically the same thing...:wink:

    Daniel.
     
  10. Mar 4, 2005 #9

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    No,no,as i just said,your answer is true as well.Just for the first.For the second,the "k" should go from 1------>8.

    Daniel.
     
    Last edited: Mar 4, 2005
  11. Mar 4, 2005 #10
    show me how the second one looks I dont understand from 2-8?
     
  12. Mar 4, 2005 #11

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    [tex] \sum_{k=1}^{8}(2k+2) [/tex] produces the same terms as the ones you had.

    Daniel.
     
    Last edited: Mar 4, 2005
  13. Mar 4, 2005 #12
    how come 2 and 8 are right the series didnt start with 2 or end at 8
     
  14. Mar 4, 2005 #13

    dextercioby

    User Avatar
    Science Advisor
    Homework Helper

    It's "+1" --------->"+8".It was a tiny mistake.I've edited my posts.

    [tex] (2k+2)|_{k=1}=2\times 1+2=4 [/tex]
    -----------------
    [tex] (2k+2)|_{k=8}=2\times 8+2=18 [/tex]

    Okay?

    Daniel.
     
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Have something to add?



Similar Discussions: Summand part in summation notation
  1. Summation proof (Replies: 4)

  2. Can the summation. (Replies: 17)

  3. Summation of torques (Replies: 1)

  4. Vector notation (Replies: 3)

  5. Dirac Notation (Replies: 1)

Loading...