Đáp án:
Giải thích các bước giải:
\[\begin{array}{l}
y = \frac{{x + 2}}{{x + 5m}};y' = \frac{{5m - 2}}{{{{\left( {x + 5m} \right)}^2}}}\\
Hs\,dong\,bien\,tren\,\left( { - \infty ; - 10} \right) \Leftrightarrow y' > 0\,\,\,\forall x \in \left( { - \infty ; - 10} \right)\\
\Leftrightarrow \left\{ \begin{array}{l}
5m - 2 > 0\\
- 5m \notin \left( { - \infty ; - 10} \right)
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
m > \frac{2}{5}\\
- 5m \ge - 10
\end{array} \right. \Leftrightarrow \left\{ \begin{array}{l}
m > \frac{2}{5}\\
m \le 2
\end{array} \right.\\
\Leftrightarrow \frac{2}{5} < m \le 2
\end{array}\]
