Polynomial and roots in complex s-plane

Discussion in 'Homework Help' started by shteii01, Feb 14, 2011.

  1. shteii01

    Thread Starter AAC Fanatic!

    Feb 19, 2010
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    I have a polynomial: p1=s^3+2s^2+(K+2)s+7
    I did a Routh table, I found values of K for which roots of this polynomial are in the left hand side of the imaginary axis.

    Now. The imaginary axis is moved to -2. I need to find range of value of K for which the roots of polynomial lie to the left of -2.

    I put s+2 instead of s, my polynomial now looks like this: p2=(s+2)^3+2(s+2)^2+(K+2)(s+2)+7
    I worked it out, did Routh table, found values of K.

    My question is this. How do I relate the values of K from p2 to p1?
     
  2. Georacer

    Moderator

    Nov 25, 2009
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    Can you post the two formulas you found for each K? Maybe we can extract an expression.
     
  3. shteii01

    Thread Starter AAC Fanatic!

    Feb 19, 2010
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    I went over this with my professor. He ran into the same thing I did. The homework was due today so I already turned it in. Thank you for looking into it.
     
  4. Georacer

    Moderator

    Nov 25, 2009
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    Please post your answers, so that the rest of the forum can benefit from them in the future.

    (is the use of benefit correct?)
     
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