a) ĐKXĐ: \(x^2-5x+6\ge0\)
\(\Leftrightarrow\left(x-3\right)\left(x-2\right)\ge0\)
\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x-3\ge0\\x-2\ge0\end{matrix}\right.\\\left\{{}\begin{matrix}x-3\le0\\x-2\le0\end{matrix}\right.\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x\ge3\\x\ge2\end{matrix}\right.\\\left\{{}\begin{matrix}x\le3\\x\le2\end{matrix}\right.\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x\ge3\\x\le2\end{matrix}\right.\)
b) ĐK: \(x\ge0\)
\(\sqrt{x^2+4x+4-2}=x\)
\(\Leftrightarrow x^2+4x+4-2=x^2\)
\(\Leftrightarrow4x+2=0\)
\(\Leftrightarrow x=\frac{-1}{2}\)
