find the derivative of $\displaystyle \frac{4}{x+1}$ using first principles

$\displaystyle \frac {f(x+h)-f(x)}{h} = \frac {4}{(x+h)+1} - \frac{4}{x+1} * \frac{1}{h}$

this is as far as i can get i know to find a common demon i just can't get the right answer