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Math Help - Algebra2 - Complex Numbers

  1. #1
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    Algebra2 - Complex Numbers

    I'm currently struggling with complex numbers alot, and dont really know where to start. Any help would be much appreciated.



    Write the complex number i^15 in the usual a + bi form;

    Write the complex number 2-i/5+i in the usual a + bi form
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  2. #2
    Super Member Aryth's Avatar
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    Well, i^{15} = -i so:

    i^{15} = 0 + -1(i) = 0 - i (If it MUST be in a + bi, then use 0 + -i, if not, then use 0 - i or just -i).

    2 - \frac{i}{5} + i

    2 - \frac{i}{5} + \frac{5i}{5} = 2 - \frac{4i}{5}

    In a + bi form:

    2 + -\frac{4}{5}i
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  3. #3
    A riddle wrapped in an enigma
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    Quote Originally Posted by 14041471 View Post
    Write the complex number 2-i/5+i in the usual a + bi form
    My guess is you meant this:

    \frac{2-i}{5+i}


    But I could be wrong.


    \frac{2-i}{5+i} \cdot \frac{5-i}{5-i}=\frac{10-5i-2i+1}{25+1}=\frac{11-7i}{26}=\frac{11}{26}-\frac{7}{26}i
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  4. #4
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    Thanks

    You were right. Thanks
    Quote Originally Posted by masters View Post
    My guess is you meant this:

    \frac{2-i}{5+i}


    But I could be wrong.


    \frac{2-i}{5+i} \cdot \frac{5-i}{5-i}=\frac{10-5i-2i+1}{25+1}=\frac{11-7i}{26}=\frac{11}{26}-\frac{7}{26}i
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