a) \(\left(x-3\right)\left(x+3\right)+x\left(5-x\right)+4=0\)\(\Leftrightarrow x^2-9+5x-x^2+4=0\)\(\Leftrightarrow5x=5\)\(\Leftrightarrow x=1\)b) \(2x^3-x^2-2x=-1\)\(\Leftrightarrow x^2\left(2x-1\right)-\left(2x-1\right)=0\)\(\Leftrightarrow\left(2x-1\right)\left(x^2-1\right)=0\)\(\Leftrightarrow\left(2x-1\right)\left(x-1\right)\left(x+1\right)=0\)\(\Leftrightarrow\left[{}\begin{matrix}2x-1=0\\x-1=0\\x+1=0\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=1\\x=-1\end{matrix}\right.\)Câu trả lời: a) \(\left(x-3\right)\left(x+3\right)+x\left(5-x\right)+4=0\)\(\Leftrightarrow x^2-9+5x-x^2+4=0\)\(\Leftrightarrow5x=5\)\(\Leftrightarrow x=1\)b) \(2x^3-x^2-2x=-1\)\(\Leftrightarrow x^2\left(2x-1\right)-\left(2x-1\right)=0\)\(\Leftrightarrow\left(2x-1\right)\left(x^2-1\right)=0\)\(\Leftrightarrow\left(2x-1\right)\left(x-1\right)\left(x+1\right)=0\)\(\Leftrightarrow\left[{}\begin{matrix}2x-1=0\\x-1=0\\x+1=0\end{matrix}\right.\)\(\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{1}{2}\\x=1\\x=-1\end{matrix}\right.\)