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Thread: HSC 2017 MX2 Marathon

  1. #101
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    Re: HSC 2017 MX2 Marathon

    Not sure if its me or the book error but I had a complex number question

    (6+i)(a+bi)=2

    My solution for



    My book has a different solution to that.
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  2. #102
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    Re: HSC 2017 MX2 Marathon

    Quote Originally Posted by davidgoes4wce View Post
    Not sure if its me or the book error but I had a complex number question

    (6+i)(a+bi)=2

    My solution for



    My book has a different solution to that.
    I also got the same answer as you.
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  3. #103
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    Re: HSC 2017 MX2 Marathon

    I spent 5 minutes on this and couldn't solve it.





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  4. #104
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    Re: HSC 2017 MX2 Marathon

    I think my book has done another mistake. (The book has made a few mistakes so I'm just checking with people on here)
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  5. #105
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    Re: HSC 2017 MX2 Marathon

    i got an

    x+yi


    my x-component was :



    I haven't solved the y-component yet. Want to get 'x' right before I do the y.
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  6. #106
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    Re: HSC 2017 MX2 Marathon

    The book's answer is right, you can check it by squaring it to get 5 + i.

  7. #107
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    Re: HSC 2017 MX2 Marathon

    Quote Originally Posted by davidgoes4wce View Post
    I spent 5 minutes on this and couldn't solve it.





    x^2 - y^2 + 2xyi = 5+i

    Comparing real and imaginary
    2xy = 1
    y = 1/2x

    x^2 - y^2 = 5
    x^2 - 1/4x^2 = 5
    4x^4 - 20x^2 - 1 = 0
    x^2 = (20 +- sqrt(20^2 - 4(4)(-1))/2(4)
    x^2 = (20+- sqrt(416))/8
    x^2 = (20 +- 4sqrt(26))/8
    x^2 = (5 +- sqrt(26))/2

    But x is real so take the positive case only
    x = +- sqrt[(5+sqrt26)/2]
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  8. #108
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    Re: HSC 2017 MX2 Marathon

    Quote Originally Posted by davidgoes4wce View Post
    I spent 5 minutes on this and couldn't solve it.





    http://i.imgur.com/xWfCJry.jpg
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