\(\Leftrightarrow x^4-x^3-x^2+x^3-x^2-x-3x^2+3x+3\le0\)
\(\Leftrightarrow x^2\left(x^2-x-1\right)+x\left(x^2-x-1\right)-3\left(x^2-x-1\right)\le0\)
\(\Leftrightarrow\left(x^2+x-3\right)\left(x^2-x-1\right)\le0\)
\(\Leftrightarrow\left[{}\begin{matrix}\frac{-1-\sqrt{13}}{2}\le x\le\frac{1-\sqrt{5}}{2}\\\frac{-1+\sqrt{13}}{2}\le x\le\frac{1+\sqrt{5}}{2}\end{matrix}\right.\)