\(ĐK:x^2+2x-3\ge0\Leftrightarrow\left(x-1\right)\left(x+3\right)\ge0\\ \Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x-1\ge0\\x+3\ge0\end{matrix}\right.\\\left\{{}\begin{matrix}x-1\le0\\x+3\le0\end{matrix}\right.\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x\ge1\\x\le-3\end{matrix}\right.\left(A\right)\)