اگر $f\left( x \right)=\left\{ \begin{matrix}
-\frac{1}{2}\,\,\,\,\,\,\,\,\,\,\,\,;\,\,\,\,\,\,\,\,\,\,x\lt 0 \\
2x\,\,\,\,\,\,\,\,\,\,\,\,\,\,;\,\,\,\,\,\,\,\,\,x\ge 0 \\
\end{matrix} \right.$ و $g\left( x \right)=\left\{ \begin{matrix}
-2x\,\,\,\,\,\,\,\,\,\,\,\,;\,\,\,\,\,\,\,\,\,\,x\lt 0 \\
1\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,;\,\,\,\,\,\,\,\,\,\,x\ge 0 \\
\end{matrix} \right.$، کدام تابع در $x=0$ پیوسته است؟