# Math Help - derivative.

1. ## 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.

2. $g(x) = 9x^2 + 12x + 4$

$g'(x) = 18x+12$

3. Originally Posted by skeeter
$g(x) = 9x^2 + 12x + 4$

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