\(-3\le x\le1\)
\(\sqrt{3-3x}=2+\sqrt{3+x}\)
\(\Leftrightarrow3-3x=4+3+x+4\sqrt{3+x}\)
\(\Leftrightarrow-x-1=\sqrt{3+x}\)
\(\Leftrightarrow\left\{{}\begin{matrix}-x-1\ge0\\\left(-x-1\right)^2=3+x\end{matrix}\right.\) \(\Leftrightarrow\left\{{}\begin{matrix}x\le-1\\x^2+x-2=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=1\left(l\right)\\x=-2\end{matrix}\right.\)