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HL maths edco sample e paper 1 complex numbers q

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  • 03-06-2013 9:33pm
    #1
    EvM
    Registered Users Posts: 55 ✭✭


    Use De Moivre's theorem to solve for 3 roots of unity, 1, w and w^2.

    Hence show that the sum of these roots is zero.


    I'm not sure how to even go about doing this question, could someone please show me what to do?

    And what in gods name is a root of unity?


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    #2
    maroon77
    Registered Users Posts: 12 ✭maroon77


    very similar to LC HL q3 2003, check examinations.ie for marking scheme.

    good luck


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    #3
    EvM
    Registered Users Posts: 55 ✭✭EvM


    Thanks just checked it there, but in that question it gave you the equation that they were the roots of. If they're the roots if unity, what does that mean?


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    #4
    Moody_mona
    Registered Users Posts: 1,107 ✭✭✭Moody_mona


    z^3=1

    So you're solving using De moivre for z=(1+0i)^1/3


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    #5
    lostatsea
    Registered Users Posts: 320 ✭✭lostatsea


    You guys make me laugh with question after question from your Edco papers. I've been working through 100's of really good questions since November with all the solutions online. Why are you putting yourselves through such agony?


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    #6
    EvM
    Registered Users Posts: 55 ✭✭EvM


    Moody_mona wrote: »
    z^3=1

    So you're solving using De moivre for z=(1+0i)^1/3

    Ah awesome, so that's what it means. Thanks a bunch :)!


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