\(\Delta=1-4\left(m+1\right)=-4m-3\ge0\Rightarrow m\le\frac{-3}{4}\)
Theo Viet ta có: \(\left\{{}\begin{matrix}x_1+x_2=1\\x_1x_2=m+1\end{matrix}\right.\)
\(x_1x_2\left(x_1x_2-2\right)=3\left(x_1+x_2\right)\)
\(\Leftrightarrow\left(m+1\right)\left(m-1\right)=3\)
\(\Leftrightarrow m^2=4\)
\(\Rightarrow\left[{}\begin{matrix}m=-2\\m=2\left(l\right)\end{matrix}\right.\)