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Simple complex number

  1. Jun 14, 2009 #1
    hey guys ive got a problem

    If z = 3− i and w = 1+3i, evaluate Im (z∗w)/(2z − 3w)


    my attempt... ill do top first (3+i)(1+3i)=3+9i+i+3i^2=10i???

    bottom=3-2i-3+9i=7i therefore answer equals 10/7 however answer is 3/13. could someone please help. thanks
     
  2. jcsd
  3. Jun 14, 2009 #2

    rock.freak667

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    (3-i)(1+3i) is the numerator, work that out again.

    Also for 2z, why did you have 3-2i instead of 2(3-i)=6-2i ?
     
  4. Jun 14, 2009 #3
    o soz that * is not a multiple sign its the conjurate sign i think. o yeh the bottom should be (6-2i)-(3+9i)=3+7i. is that right??
     
  5. Jun 14, 2009 #4

    Cyosis

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    No [itex]-2i-9i \neq -7i[/itex]. The numerator has been calculated correctly.
     
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