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Math Help - Multiplying complex numbers

  1. #1
    Rae
    Rae is offline
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    Multiplying complex numbers

    Write the complex number in the form a + bi.

    [1 + sq rt (-2)] * [2 + sq rt (-4)]


    The answer I get is:

    2 + 2*sq rt(2) + [2 + 2*sq rt(2)]i

    The answer in the book is:

    [2 - 2*sq rt(2)] + [2 + 2*sq rt(2)]i


    I'm sorry if my typing is confusing. I don't know how to type the math symbols.
    Thanks for any help.
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  2. #2
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    (1+\sqrt2i)(2+2i)=2+2\sqrt2i+2i-2\sqrt2=(2-2\sqrt2)+(2\sqrt2+2)i
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