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Homework Help: Complex numbers

  1. Oct 28, 2005 #1

    UnD

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    Lol sry got stuck on this past quesiton
    consider z^2 + az+ (1+i)=0 , find the complex number a, given that i is a root of the equation
    so (x-i) is a factor thing:yuck:

    z= -a +_ sqroot a^2 -4 -4i
    ----------------------------
    2
    then let sqroot a^2 -4 - 4I =c+ib
    lol i don't know where to go after that.
     
  2. jcsd
  3. Oct 28, 2005 #2

    HallsofIvy

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    Science Advisor

    Well actually, z- i is a factor, not x-i!:biggrin:
    Given that z-i is a factor we can divide by it:
    z-i divides into z2+ az+ (1+i)
    z+ (a+i) times with a remainder of (1+a)i . If i really is a root of the equation, then that remainder must be 0. So a must be ____.
     
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