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Math Help - [HELP] Solving Complex solutions of Quadratic Equations

  1. #1
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    [HELP] Solving Complex solutions of Quadratic Equations

    Anyone knows how to solve this problem?

    Find all solutions of the equation and express them in form of a+bi

    1.x + 9 = 0

    2.9x + 4 = 0

    3.x +1/2x + 1 = 0

    I really have no idea what to do..

    Thanks in advance!
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  2. #2
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    Re: [HELP] Solving Complex solutions of Quadratic Equations

    Do you not know how to take square roots? If x^2+ 9= 0 then x^2= -9 and you take the square root of both sides.

    If 9x^2+ 4= 0, then 9x^2= -4, x^2= -\frac{4}{9}. Of course, you need to know that the square root of -1 is "i".

    For the last one, I presume that is x^2+ (1/2)x+ 1= 0. Do you know the "quadratic formula"? If ax^2+ bx+ c= 0, then x= \frac{-b\pm\sqrt{b^2- 4ac}}{2a}. Here a= 1, b= 1/2, c= 1. x= \frac{-1/2\pm \sqrt{1/4- 4}}{2}= \frac{-1/2\pm \sqrt{-15/4}}{2}= -\frac{1}{4}\pm\frac{\sqrt{-15}}{4}= -\frac{1}{4}\pm \frac{\sqrt{15}}{4}i.
    Thanks from Deveno
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  3. #3
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    Re: [HELP] Solving Complex solutions of Quadratic Equations

    Thank you man! Really help me!!
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