\(\left(x+2\right)\left(x+5\right)< 0\)
\(\Rightarrow\left[{}\begin{matrix}x+2>0;x+5< 0\\x+2< 0;x+5>0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}x>-2;x< -5\\x< -2;x>-5\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}-2< x< -5\left(loại\right)\\-5< x< -2\left(tm\right)\end{matrix}\right.\)
Vậy \(-5< x< -2.\)