\(\Leftrightarrow x^4+x^3-7x^2-5x^3-5x^2+35x+2x^2+2x-14=0\)
\(\Leftrightarrow x^2\left(x^2+x-7\right)-5x\left(x^2+x-7\right)+2\left(x^2+x-7\right)=0\)
\(\Leftrightarrow\left(x^2-5x+2\right)\left(x^2+x-7\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x^2-5x+2=0\\x^2+x-7=0\end{matrix}\right.\)