Giai bất phương trình sau :
\(\frac{x^2-7x+12}{-x+2}\le0\)
\(\Leftrightarrow\frac{\left(x-4\right)\left(x-3\right)}{-x+2}\le0\)
\(\Leftrightarrow\frac{\left(x-4\right)\left(x-3\right)}{x-2}\ge0\)
\(\Rightarrow\left[{}\begin{matrix}x\ge4\\2< x\le3\end{matrix}\right.\)