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Math Help - derivative.

  1. #1
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    derivative.

    I have an equation

     y =\frac{2x-5}{(3x+2)^2}

    so i have to differentiate it.

    I think i am supposed to use the quotient rule

     (\frac {f}{g})' = \frac{gf'-fg'}{g^2}


    but i am confused about g'

    In trying to differentiate it i come up with this
    Expanded g.

     (3x+2)(3x+2)


    Then multiply out


     = 9x^2 +6x+6x+4

    =9x^2+12x

    =18x +12x

    so g' =20 x

    Is this correct? I have a feeling ive done somthing wrong. Im just trying to work out g' so i can plug it into the equation.
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  2. #2
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    g(x) = 9x^2 + 12x + 4

    g'(x) = 18x+12
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  3. #3
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    Quote Originally Posted by skeeter View Post
    g(x) = 9x^2 + 12x + 4

    g'(x) = 18x+12
    thanks.
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