\(x^4-9x^3+x^2-9x=0\)\(\Leftrightarrow x\left(x^2+1\right)\left(x-9\right)=0\)\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=9\end{matrix}\right.\)Câu trả lời: \(x^4-9x^3+x^2-9x=0\)\(\Leftrightarrow x\left(x^2+1\right)\left(x-9\right)=0\)\(\Leftrightarrow\left[{}\begin{matrix}x=0\\x=9\end{matrix}\right.\)