\(a,\Rightarrow3x\left(x-4\right)+12\left(x-4\right)=0\\ \Rightarrow3\left(x+4\right)\left(x-4\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\\ b,\Rightarrow x^2\left(x-2\right)-\left(x-2\right)=0\\ \Rightarrow\left(x^2-1\right)\left(x-2\right)=0\\ \Rightarrow\left(x-1\right)\left(x+1\right)\left(x-2\right)=0\\ \Rightarrow\left[{}\begin{matrix}x=1\\x=-1\\x=2\end{matrix}\right.\)
a) \(\Rightarrow3x\left(x-4\right)+12\left(x-4\right)=0\)
\(\Rightarrow3\left(x-4\right)\left(x+4\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=4\\x=-4\end{matrix}\right.\)
b) \(\Rightarrow\left(x-2\right)\left(x^2-1\right)=0\)
\(\Rightarrow\left(x-2\right)\left(x-1\right)\left(x+1\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x=2\\x=1\\x=-1\end{matrix}\right.\)
