1: \(x^2+4x+3>0\)
=>(x+1)(x+3)>0
TH1: \(\left\{{}\begin{matrix}x+1>0\\x+3>0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>-1\\x>-3\end{matrix}\right.\Leftrightarrow x>-1\)
TH2: \(\left\{{}\begin{matrix}x+1< 0\\x+3< 0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x< -1\\x< -3\end{matrix}\right.\)
=>x<-3
2: \(3x^2+5x+2< 0\)
=>\(3x^3+3x+2x+2< 0\)
=>3x(x+1)+2(x+1)<0
=>(x+1)(3x+2)<0
TH1: \(\left\{{}\begin{matrix}x+1>0\\3x+2< 0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x>-1\\x< -\dfrac{2}{3}\end{matrix}\right.\)
=>\(-1< x< -\dfrac{2}{3}\)
TH2: \(\left\{{}\begin{matrix}x+1< 0\\3x+2>0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x< -1\\x>-\dfrac{2}{3}\end{matrix}\right.\Leftrightarrow x\in\varnothing\)
