\(\left(x^2+x\right)^2+\left(x^2+x\right)-6=0\)
\(\Leftrightarrow\left(x^2+x\right)^2-2\left(x^2+x\right)+3\left(x^2+x\right)-6=0\)
\(\Leftrightarrow\left(x^2+x\right)\left(x^2+x-2\right)+3\left(x^2+x-2\right)=0\)
\(\Leftrightarrow\left(x^2+x+3\right)\left(x^2+x-2\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2+x+3=0\\x^2+x-2=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2+x+\dfrac{1}{4}+\dfrac{11}{4}=0\\\left(x+2\right)\left(x-1\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}\left(x+\dfrac{1}{2}\right)^2=-\dfrac{11}{4}\left(L\right)\\\left(x+2\right)\left(x-1\right)=0\end{matrix}\right.\)
\(\Leftrightarrow\left[{}\begin{matrix}x+2=0\\x-1=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=-2\\x=1\end{matrix}\right.\)
Vậy \(\left[{}\begin{matrix}x=-2\\x=1\end{matrix}\right.\)
