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Homework Help: Recursie Algorithms. Is my solution ok?

  1. Apr 28, 2004 #1
    Code (Text):

    This is the question I must solve;
    Solve the given recurrence relation for the given inital conditions.
    (This means give a formula in terms of n, not in terms of previous entries)
    a[sub]n[/sub] = 7a[sub]n-1[/sub] - 12a[sub]n-2[/sub]
    a[sub]0[/sub] = 3 a[sub]1[/sub] = 10
    Now I am not sure what that means but I think this will solve the question

    let me know if I am not even close;
    Input = n
    Output = X(n)

    procdure find(n)
     if n = 3 or n = 10 then
      return (n)
     return(find(n-1)+find(n-2))
    end find(n)
     
     
  2. jcsd
  3. Apr 28, 2004 #2

    jamesrc

    User Avatar
    Science Advisor
    Gold Member

    I'm fairly certain that what they are looking for is a single equation for a as a function of n. Simple example:

    Given: an = an-1 + 1
    and a0 = 11

    Then:

    an = 11+n
     
  4. Apr 29, 2004 #3
    Code (Text):

    Solve the given recurrence relation for the given inital conditions.
    (This means give a formula in terms of n, not in terms of previous entries)
    a[sub]n[/sub] = 7a[sub]n-1[/sub] - 12a[sub]n-2[/sub]
    a[sub]0[/sub] = 3 a[sub]1[/sub] = 10

    So;
    a[sub]2[/sub] = 7a[sub]2-1[/sub] - 12a[sub]2-2[/sub]
    a[sub]2[/sub] = 7a[sub]1[/sub] - 12a[sub]0[/sub]
    a[sub]2[/sub] = 7(10) - 12(3)
    a[sub]2[/sub] = 70 - 36
    a[sub]2[/sub] = 34?
     
     
  5. Apr 29, 2004 #4
  6. Apr 29, 2004 #5
    Oh not that again I thought I was done with that. Ok I know what to do thanks again.
     
  7. Apr 29, 2004 #6
    I come up with all mixed fractions when I get a using the same method as I did on that problem? So that does not work.
     
  8. Apr 29, 2004 #7
    It works. You need to work on your algebra.
     
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