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Math Help - Xn Solving a difference equation

  1. #1
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    Xn Solving a difference equation

    Find Xn

    X(n+2) - 5X(n+1) +6Xn = 2*3^n

    please help
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  2. #2
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    Quote Originally Posted by Knut-o View Post
    Find Xn

    X(n+2) - 5X(n+1) +6Xn = 2*3^n

    please help
    This is a difference equation with constant coefficients. Your class notes should tell you what to do.

    Find the solution to X_{n+2} - 5 X_{n+1} + 6 X_n = 0.

    Construct a particular solution.

    Now add those two solutions together.

    If you need more help please show what you've done and say where you get stuck.
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  3. #3
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    Im stuck at the particular solution. Am I suppose to use "A * E*3^n" at the left side to find it?
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  4. #4
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    Quote Originally Posted by Knut-o View Post
    Im stuck at the particular solution. Am I suppose to use "A * E*3^n" at the left side to find it?
    Since 3^n is part of the homogenous solution you can't try to construct a particular solution of the form X_n = \alpha 3^n. Instead you have to try a particular solution of the form X_n = \alpha {\color{red}n} 3^n.
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  5. #5
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    ok, thank you
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