Answer
$$-\frac{1}{4}$$
Work Step by Step
\begin{align*}
\lim _{x \rightarrow 0} \frac{\frac{1}{2+x}-\frac{1}{2}}{x}&=\lim _{x \rightarrow 0} \frac{2-(2+x)}{2 x(2+x)}\\
&=\lim _{x \rightarrow 0} \frac{-1}{4+2 x}\\
&=-\frac{1}{4}
\end{align*}