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Series of partial sums

  1. Nov 8, 2016 #1
    1. The problem statement, all variables and given/known data
    t5672v.jpg



    2. Relevant equations

    an= bn - bn+1 which is already in the problem

    3. The attempt at a solution

    i did partial fractions but then i got stuck at

    16/12 [4n-5] - 16/12 [4n+7] that part about bn confuses me please someone explain in detail
     
  2. jcsd
  3. Nov 8, 2016 #2

    Mark44

    Staff: Mentor

    Where's the equation you're working with?
    Starting from ##\frac{16}{16n^2 + 8n - 35} = \frac{A}{4n - 5} + \frac{B}{4n + 7}##, multiply both sides by ##16n^2 + 8n - 35## to clear out all of the denominators. Then solve for the constants A and B.
     
  4. Nov 8, 2016 #3
    i did and i get 16/12 for A and - 16/12 for B as i indicated above the problem is what is the next step
     
  5. Nov 9, 2016 #4

    vela

    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
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    I think there's a typo in the problem. It should say ##a_n = b_n - b_{n+3}##.
     
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