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    I'm doing some extra questions out of a different textbook as revision, so i'm not sure if I should actually be able to do this or not...

    So if someone could give me a few hints as to what to do then if I don't recognise it i'll presume I don't need to know how to do this.

    Find the roots of the equation z^{2}+4z+7 = 0 giving your answers on the form p \pm i\sqrt q.

    Now I take it they will be complex conjugates, but don't know where to start.
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    Quadratic formula.
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    Omg. I can't believe I didn't think of that... I think I was expecting it to be harder than it was... Thats my excuse anyway :p:
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    We've all done it, don't worry. :p:
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    What about cubics? Will there always be an easier factor to spot for the third root (ie not a fraction)? So then you can form a quadratic and apply the same method?
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    For the questions they give you, there should be.
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    its either that or they give you one the the complex roots, then you use the fact that if
    (a+bi) is a root then (a-bi) is also a root

    so the quadratic factor would be (z-a-bi)(z-a+bi)
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    Oooo ok cool.
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    you could also find the perfect square(?) so (z+a)^2=b
    =)
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    (Original post by Hyeree)
    you could also find the perfect square(?) so (z+a)^2=b
    =)
    Yep - this is called "completing the square" in English.
 
 
 
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Updated: March 8, 2008

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