How do you differentiate this with respect to s

Quote:

Originally Posted by adam_leeds

How do you differentiate the following with respect to s:

http://i47.tinypic.com/30js935.jpg

Thanks

Let $y = e^{ \lambda ( \frac{ p}{1-qs} - 1 ) }$

$lny = \lambda ( \frac{ p}{1-qs} - 1 )$

$lny = \lambda p (1-qs)^{-1} - \lambda$

Implicitly differentiate

$\frac{1}{y} y^{ \prime } = \lambda p (1-qs)^{-2} * q$

Resulting in

$y^{ \prime } = \lambda p q (1-qs)^{-2} ( e^{ \lambda ( \frac{ p}{1-qs} - 1 ) } )$