1. ## first principles

Hey i need help with this question:

Find the derivative of the function $\displaystyle f(x)=1/(x+2)$ by using first principles.

We have to use first principles, please and thanks you.

2. If the limit exists, then

$\displaystyle f'(x) = \mathop {\lim }\limits_{\Delta x \to 0} \frac{{f\left( {x + \Delta x} \right) - f(x)}} {{\Delta x}}.$

And $\displaystyle f\left( {x + \Delta x} \right) = \frac{1} {{\left( {x + \Delta x + 2} \right)}}.$ You may perform from there the calculations.