\(\left(x-1\right)\left(x+2\right)\left(x^3+4x\right)=0\)
\(\Rightarrow\left[{}\begin{matrix}x-1=0\\x+2=0\\x^3+4x=0\end{matrix}\right.\) \(\Rightarrow\left[{}\begin{matrix}x=1\\x=-2\notin N\\x=0\end{matrix}\right.\)
\(\Rightarrow A=\left\{0;1\right\}\)