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Thread: Root of Unity

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    Question Root of Unity

    I am currently doing complex root of unity questions from terry lee's 4u book and while going through some exercises i keep noticing the formula x^2-S(x)+P keeps popping up. I understand that is the sum and product of roots, but when do we use this formula in questions?

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    I love trials pikachu975's Avatar
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    Re: Root of Unity

    I don't think I've ever used that for root of unity do you have an example?
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    Re: Root of Unity

    Quote Originally Posted by Sokc View Post
    I am currently doing complex root of unity questions from terry lee's 4u book and while going through some exercises i keep noticing the formula x^2-S(x)+P keeps popping up. I understand that is the sum and product of roots, but when do we use this formula in questions?

    Hmm..I think I've seen a couple of questions like that but I might be wrong. If I recall correctly, I mostly used that formula to factorise expressions such as into a product of linear or quadratic factors. It's also commonly used for proving some random trigonometric identity but I can't think of any examples off the top of my head.

    For example (I probably made some errors along the way here since I wasn't that great at 4U),




























    Idk if that made any sense but hope that helps. This was the first time I used LaTeX so the input is killing me. Let me know if you need more help.
    Last edited by captainhelium; 11 Nov 2017 at 5:13 PM.
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    Re: Root of Unity

    If you were asking for roots of UNITY (meaning z^n=1) then you wouldn't have to apply that formula. Its more of a polynomial thing.

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