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Homework Help: Using PMI prove un=((-1)^(n+1))/3 + (2^n)/3

  1. Aug 30, 2011 #1
    Solved thank you.

    Thank you for all the help just a little forgetful mistake.
    Last edited: Aug 30, 2011
  2. jcsd
  3. Aug 30, 2011 #2
    You didn't use the induction hypothesis yet. You need to sub

    [tex]u_n = \frac{(-1)^{n+1}+2^n}{3}[/tex]


    [tex]u_{n-1} = \frac{(-1)^n+2^{n-1}}{3}[/tex]
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