Câu trả lời:
a)\(x\cdot\left(4x^2\right)=0\)\(\Rightarrow\left\{{}\begin{matrix}x=0\\4x^2-1=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0\\\left(2x-1\right)\left(2x+1\right)=0\end{matrix}\right.\Leftrightarrow\left\{{}\begin{matrix}x=0\\x=\dfrac{1}{2}\\x=\dfrac{-1}{2}\end{matrix}\right.\)