h/s trên đồng biến khi :
\(\dfrac{m-3}{m+5}>0\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}m-3>0\\m+5>0\end{matrix}\right.\\\left\{{}\begin{matrix}m-3< 0\\m+5< 0\end{matrix}\right.\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}m>3\\m< -5\end{matrix}\right.\)