Differentiation when x=-1

[IloveManUtd]

Given that y= (2x+3)[sup:1rlan0cz]5[/sup:1rlan0cz](x+2)[sup:1rlan0cz]8[/sup:1rlan0cz], find the value of dy/dx when x=-1?

I'm confused with this question: where and when do I put -1 in?

 

[BigGlenntheHeavy]

$\displaystyle y \ = \ f(x) \ = \ (2x+3)^5(x+2)^8$

$\displaystyle f'(x) \ = \ ?$

$\displaystyle f'(-1) \ = \ ?$