
Derivatives problem
I'm trying to differentiate the following..
$\displaystyle \frac{dG}{dz} = \frac{1a}{1+a} * \frac{2a}{(1az)^{2}}$
z is evaluated at 1 according to the Leibniz notation.
The answer is $\displaystyle \frac{2a}{1a^2}$
I'm not quite sure how to get there.
$\displaystyle (1az)^{2} $ would be differentiated with the chain rule to give..
$\displaystyle 2(1az)^{3} * (a) = \frac{2a}{(1az)^{3}} $
Does the z disappear because we substitute in the value 1 at this point?
I'm not sure how to get rid of the (1+a) in the denominator.

Its already differentiated, can't you see?
dG/dz means that you already differendiated it. Now just substitute for z=1.
Now you got:
$\displaystyle \frac{dG}{dz} _{z=1}= \frac{1a}{1+a} * \frac{2a}{(1a)^{2}}=\frac{1a}{1+a}*\frac{2a}{(1a)*(1a)}=\frac{2a}{(1a)*(1+a)}$