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Solve the difference equation?

  1. Jul 12, 2013 #1
    Solve the difference equation yn+1=-0.9yn in terms of the initial value y0.

    y1=-0.9y0
    y2=-0.9y1=(-0.9)2y0
    yn=(-0.9)ny0
    Is this the answer? Because the answer in the textbook says yn=(-1)n(0.9)ny0. Please help.
     
  2. jcsd
  3. Jul 12, 2013 #2
    Your solution and the solution in your textbook are the same.
     
  4. Jul 14, 2013 #3

    HallsofIvy

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    [tex](ab)^n= a^n b^n[/tex]
     
  5. Jul 14, 2013 #4

    jedishrfu

    Staff: Mentor

    The textbook wrote it that way to make it clear that even terms are positive and odd terms are negative.
     
  6. Jul 15, 2013 #5

    HallsofIvy

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    And, as I pointed out in your previous thread, you are not finished until you have shown that your solution does satisfy the equation. If yn= (-0.9)ny0 then -0.9yn= -0.9((-0.9)ny0)= (-0.9)n+1y0= yn+1.
     
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