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Math Help - quadratics help needed

  1. #1
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    quadratics help needed

    I need to solve for x in these two question;
    x: -3x2 + 4x = 4
    x: x2 + 3x + 4 = 0

    I'm quite sure there will be two awnsers for each question
    I tried plugging in the numbers into this formula -b+/- sqrt> b^2 -4(a)(c)/2a
    i need somebodies help because my arithmatic is bad, and i cant seem to get a whole number as my awnser so im stuck
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  2. #2
    Bar0n janvdl's Avatar
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    Quote Originally Posted by 14041471 View Post
    I need to solve for x in these two question;
    x: -3x2 + 4x = 4
    x: x2 + 3x + 4 = 0

    I'm quite sure there will be two awnsers for each question
    I tried plugging in the numbers into this formula -b+/- sqrt> b^2 -4(a)(c)/2a
    i need somebodies help because my arithmatic is bad, and i cant seem to get a whole number as my awnser so im stuck
    Correct, they are not whole numbers, and the roots are complex.
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  3. #3
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    reply

    i no you've helped me out alot already, but i really cant awnser this question. could you solve it for me and then mabe i could see how it is like that..
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  4. #4
    Bar0n janvdl's Avatar
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    Quote Originally Posted by 14041471 View Post
    i no you've helped me out alot already, but i really cant awnser this question. could you solve it for me and then mabe i could see how it is like that..
    You said you plugged it into the quadratic formula. That is all you need to do.

    I will do the second one for you. The first one you must attempt on your own.

    x = \frac{ -b \pm \sqrt{b^2 - 4ac} }{2a}

    x = \frac{ -3 \pm \sqrt{9 - 4(1)(4)} }{2(1)}

    x = \frac{ -3 \pm \sqrt{7} }{2}

    x = -1.5 + \frac{ \sqrt{-7} }{2}
    OR
    x = -1.5 - \frac{ \sqrt{-7} }{2}

    Thus:


    x = -1.5 + \frac{ \sqrt{7} }{2}i
    OR
    x = -1.5 - \frac{ \sqrt{7} }{2}i
    Last edited by janvdl; January 1st 2009 at 12:06 PM. Reason: Forgot complex stuff
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  5. #5
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    Quote Originally Posted by 14041471 View Post
    i no you've helped me out alot already, but i really cant awnser this question. could you solve it for me and then mabe i could see how it is like that..
    It would be easier to help you and point out your mistakes if you showed the work you've done.
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