Evaluate the following limits:

1.	$\displaystyle \lim_{x\to 5} \frac{2}{(x-5)^{6}}$	=
2.	$\displaystyle \lim_{x\to 3^{+}} \frac{2}{x-3}$	=
3.	$\displaystyle \lim_{x\to -7^{-}} \frac{1}{x^{2}(x+7)}$	=
4.	$\displaystyle \lim_{x\to 0} \frac{1}{x^{2}(x+7)}$	=