1: =>(x+4)(x-3)=0
=>x=-4 hoặc x=2
2: =>(x-6)(x+1)-2(x+1)=0
=>(x+1)(x-8)=0
=>x=-1 hoặc x=8
3: =>x2-2x-3=0
=>(x-3)(x+1)=0
=>x=3 hoặc x=-1
\(1,x^2+x-12=0\\ \Leftrightarrow\left(x^2+4x\right)-\left(3x+12\right)=0\\ \Leftrightarrow x\left(x+4\right)-3\left(x+4\right)=0\\ \Leftrightarrow\left(x-3\right)\left(x+4\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=3\\x=-4\end{matrix}\right.\\ 2,\left(x-6\right)\left(x+1\right)=2\left(x+1\right)\\ \Leftrightarrow\left(x-6\right)\left(x+1\right)-2\left(x+1\right)\\ \Leftrightarrow\left(x+1\right)\left(x-6-2\right)=0\\ \Leftrightarrow\left(x+1\right)\left(x-8\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-1\\x=6\end{matrix}\right.\)
\(3,x^2-2x+1=4\\ \Leftrightarrow\left(x-1\right)^2=4\\ \Leftrightarrow\left[{}\begin{matrix}x-1=-2\\x-1=2\end{matrix}\right.\\ \Leftrightarrow\left[{}\begin{matrix}x=-1\\x=3\end{matrix}\right.\\ 4,\left(x-3\right)\left(x+3\right)=16\\ \Leftrightarrow x^2-9-16=0\\ \Leftrightarrow x^2-25=0\\ \Leftrightarrow x=\pm5\\ 5,x^2-x-6=0\\ \Leftrightarrow\left(x^2-3x\right)+\left(2x-6\right)=0\\ \Leftrightarrow x\left(x-3\right)+2\left(x-3\right)=0\\ \Leftrightarrow\left(x+2\right)\left(x-3\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=-2\\x=3\end{matrix}\right.\)
\(6,\left(2x-1\right).\dfrac{5x-10}{10}+\left(2x-1\right).\dfrac{3x+12}{6}-\left(2x-1\right)x=0\\ \Leftrightarrow\left(2x-1\right).\dfrac{x-2}{2}+\left(2x-1\right).\dfrac{x+4}{2}-\left(2x-1\right)x=0\\ \Leftrightarrow\left(2x-1\right)\left(\dfrac{x-2}{2}+\dfrac{x+4}{2}-x\right)=0\\ \Leftrightarrow\left(2x-1\right)\left(\dfrac{x-2}{2}+\dfrac{x+4}{2}-\dfrac{x}{2}\right)=0\\ \Leftrightarrow\left(2x-1\right).\dfrac{x-2+x+4-x}{2}=0\)
\(\Leftrightarrow\left(2x-1\right)\left(x+2\right)=0\\ \Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=-2\end{matrix}\right.\)
