\(1.\) \(-12\left(x-5\right)+7\left(3-x\right)=5\) \(=>-12x+60+21-7x=5\) \(=>-12x+81-7x=5\) \(=>-12x-7x+81=5\) \(=>-19x+81=5\) \(=>-19x=-76\) \(=>x=4\) \(2.\) \(\left(x-2\right).\left(x+15\right)=0\) \(=>\left[\begin{matrix}x-2=0\\x+15=0\end{matrix}\right.=>\left[\begin{matrix}x=2\\x=-15\end{matrix}\right.\) \(3.\) \(\left(7-x\right).\left(x+19\right)=0\) \(=>\left[\begin{matrix}7-x=0\\x+19=0\end{matrix}\right.=>\left[\begin{matrix}x=7\\x=-19\end{matrix}\right.\) \(4.\) \(\left|x\right|< 3\) Xét: x là số dương => x < 3 Xét: x là số âm => x < -3