Vì \(\left(2x-4\right)\left(x+4\right)< 0\)
\(\Rightarrow\left\{{}\begin{matrix}2x-4< 0\\x+4>0\end{matrix}\right.\) hoặc \(\left\{{}\begin{matrix}2x-4>0\\x+4< 0\end{matrix}\right.\)
\(\Rightarrow\left\{{}\begin{matrix}2x< 4\\x>-4\end{matrix}\right.\) hoặc \(\left\{{}\begin{matrix}2x>4\\x< -4\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}\left\{{}\begin{matrix}x< 2\\x>-4\end{matrix}\right.\\\left\{{}\begin{matrix}x>2\\x< -4\end{matrix}\right.\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}-4< x< 2\\2< x< -4\left(loai\right)\end{matrix}\right.\)
Vậy -4 < x < 2 t/m đề bài
TH1: 2x-4 < 0 => x < 4
x +4 > 0 => x > -4
=> x ∈ ∅
TH2: 2x-4 > 0 => x > 4
x +4 < 0 => x < -4
=> -4 < x < 4
