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Homework Help: Help with My complex functions

  1. May 9, 2010 #1
    Help with My complex functions :(

    1. The problem statement, all variables and given/known data
    I have to find a real part and Imaginary part of complex functions
    but I kinda stuck on this question :(


    2. Relevant equations
    f(t)=e(-1+2i)(2-i ; 3+4i)

    from this equation I have to find real part and imaginary part :(
    I need ur help guyz asap
    !!!!:) cheers


    3. The attempt at a solution
     
  2. jcsd
  3. May 9, 2010 #2

    Mark44

    Staff: Mentor

    Re: Help with My complex functions :(

    There seems to be something missing in your function. The expression on the right side doesn't have t in it. Is this the formula for your function?
    f(t) = e(-1 + 2i)t(2 - i; 3 + 4i)
     
  4. May 9, 2010 #3
    Re: Help with My complex functions :(

    true that
    the original function is
    f(t) = e(-1+2i)t[2-i ; 3+4i]
     
  5. May 10, 2010 #4

    HallsofIvy

    User Avatar
    Science Advisor

    Re: Help with My complex functions :(

    What you have written makes no sense. What is that "e" doing in your formula? Do you really mean it to just be multiplied or do you intend e^{(-1+ 2i)t}? And what is "[2-i ; 3+4i]" is this a "vector valued" function? And, if so, do you want the real and imaginary parts of each component?
     
  6. May 10, 2010 #5

    Mark44

    Staff: Mentor

    Re: Help with My complex functions :(

    Your vector-valued function can be written this way:
    f(t) = <(2 - i) e(-1 + 2i)t , (3 + 4i)e(-1 + 2i)t>

    Then split up the exponentail parts using the fact that e(a + b)t = eatebt. Use the fact that eix = cosx + isinx. These should get you started.
     
  7. May 10, 2010 #6

    Char. Limit

    User Avatar
    Gold Member

    Re: Help with My complex functions :(

    Just moved the "e"s outside of the superscript for you.
     
  8. May 10, 2010 #7

    Mark44

    Staff: Mentor

    Re: Help with My complex functions :(

    Thanks. I hadn't noticed they were superscripts also.
     
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