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Math Help - Quadratic Equations

  1. #1
    Member
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    Quadratic Equations

    5b^2 - 14b - 3 = 0
    This is what I did
    14 = 14^2 - 4 (5)(-3) / 2(5)
    14= 196 + 60 / 10
    14= 256 / 10
    How do I get the answer?

    12x^2 - 5x = 2
    I subtracted 2 and got
    12x^2 - 5x - 2 = 0
    5= 5^2 - 4 (12)(-2) / 2(12)
    5= 25 + 96 /24
    How do I get the answer?
    Thanks
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  2. #2
    MHF Contributor Mathstud28's Avatar
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    Pennsylvania
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    3,641
    Quote Originally Posted by rowdy3 View Post
    5b^2 - 14b - 3 = 0
    This is what I did
    14 = 14^2 - 4 (5)(-3) / 2(5)
    14= 196 + 60 / 10
    14= 256 / 10
    How do I get the answer?

    12x^2 - 5x = 2
    I subtracted 2 and got
    12x^2 - 5x - 2 = 0
    5= 5^2 - 4 (12)(-2) / 2(12)
    5= 25 + 96 /24
    How do I get the answer?
    Thanks
    use the quadractic equation x=\frac{-b\pm\sqrt{b^2-4ac}}{2a}

    where a,b,c and correspond to ax^2+bx+c
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  3. #3
    Member cassiopeia1289's Avatar
    Joined
    Aug 2007
    From
    chicago
    Posts
    101
    yeah, you need to set it equal to zero and then use the quadratic equation listed above.
    you've got it right except remember to square it

    so your set up for the first one will be:
    x = \frac{14 \pm \sqrt{(-14)^2 - 4(5)(-3)}}{2(5)}
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