$$f(x)= \frac{ 1+ { x }^{ 3 } + { x }^{ 6 } }{ { x }^{ 3 } } (SHOWED)f( { x }^{ 2 } )=f( { x }^{ -2 } )$$
$\left\{\begin{matrix}D=\frac{1}{EHOSWx\left(x^{6}+x^{3}+1\right)}\text{, }&E\neq 0\text{ and }W\neq 0\text{ and }O\neq 0\text{ and }H\neq 0\text{ and }S\neq 0\text{ and }x\neq 0\\D\in \mathrm{R}\text{, }&f=0\text{ and }x\neq 0\end{matrix}\right.$
$\left\{\begin{matrix}E=\frac{1}{DHOSWx\left(x^{6}+x^{3}+1\right)}\text{, }&D\neq 0\text{ and }W\neq 0\text{ and }O\neq 0\text{ and }H\neq 0\text{ and }S\neq 0\text{ and }x\neq 0\\E\in \mathrm{R}\text{, }&f=0\text{ and }x\neq 0\end{matrix}\right.$