\(\Delta'=4\left(m-1\right)^2-3\left(m^2-4m+1\right)=m^2+4m+1\)
\(\Delta'\ge0\Rightarrow\left[{}\begin{matrix}m\ge-2+\sqrt{3}\\m\le-2-\sqrt{3}\end{matrix}\right.\)
Để \(x_1;x_2\ne0\Leftrightarrow m^2-4m+1\ne0\)
Theo Viet: \(\left\{{}\begin{matrix}x_1+x_2=-\frac{4\left(m-1\right)}{3}\\x_1x_2=\frac{m^2-4m+1}{3}\end{matrix}\right.\)
\(\frac{1}{x_1}+\frac{1}{x_2}-\frac{1}{2}\left(x_1+x_2\right)=0\)
\(\Leftrightarrow\left(x_1+x_2\right)\left(\frac{1}{x_1x_2}-\frac{1}{2}\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x_1+x_2=0\\x_1x_2=2\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}-\frac{4\left(m-1\right)}{3}=0\\\frac{m^2-4m+1}{3}=2\end{matrix}\right.\) \(\Leftrightarrow\left[{}\begin{matrix}m=1\\m^2-4m-5=0\end{matrix}\right.\)
\(\Rightarrow\left[{}\begin{matrix}m=1\\m=-1\\m=5\end{matrix}\right.\)
