problem in Laplace

Discussion in 'Math' started by full, Dec 4, 2014.

  1. full

    Thread Starter Member

    May 3, 2014
    225
    2
    hello everybody
    there is some problem in Laplace :

    if do Laplace by alpha is different by my hand why?

    by alpha
    88.PNG

    by my hand
    89.jpg
     
  2. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    Check your simplification.

    You should have

     \frac {40}{s^2+6s+12}=\frac {40}{ \(s+3\)^2+\({\sqr {3}}\)^2
     
    Last edited: Dec 4, 2014
  3. full

    Thread Starter Member

    May 3, 2014
    225
    2
    yes , if use calculator will get (-3+1.732j) , (-3-1.732j)
    thanks
     
  4. t_n_k

    AAC Fanatic!

    Mar 6, 2009
    5,448
    782
    A calculator isn't necessary. The manipulation in post #2 should be readily appreciated by the observant student.
     
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  5. WBahn

    Moderator

    Mar 31, 2012
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    You need to become familiar with completing the square. You also need to stop relying on tools like Wolfram Alpha and a calculator to do your thinking for you. It's one thing to use them to verify your work or to ease the grunt work, it's another to just turn to them because you can't work it out yourself. The distinction between proper and improper use of these kinds of tools is very gray and malleable, but you want to try to develop and maintain your ability to do your own thinking.
     
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  6. cmartinez

    AAC Fanatic!

    Jan 17, 2007
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    The mind needs to solve complex logic problems to remain sharp... pretty much like muscles need a basic level of weight lifting to keep functional and the rest of the body in good shape...
     
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