what is 18x^3-63x^2+9x

I assume that you want to find the roots (zeroes) of this...so we have

18x^3-63x^2+9x = 0      divide through by 9

2x^3 - 7x^2 + x  = 0      factor

x (2x^2 - 7x + 1) = 0      one solution is x = 0

For the polynomial in the parentheses......we can use the onsite solver

$${\mathtt{2}}{\mathtt{\,\times\,}}{{\mathtt{x}}}^{{\mathtt{2}}}{\mathtt{\,-\,}}{\mathtt{7}}{\mathtt{\,\times\,}}{\mathtt{x}}{\mathtt{\,\small\textbf+\,}}{\mathtt{1}} = {\mathtt{0}} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{\,-\,}}{\frac{\left({\sqrt{{\mathtt{41}}}}{\mathtt{\,-\,}}{\mathtt{7}}\right)}{{\mathtt{4}}}}\\
{\mathtt{x}} = {\frac{\left({\sqrt{{\mathtt{41}}}}{\mathtt{\,\small\textbf+\,}}{\mathtt{7}}\right)}{{\mathtt{4}}}}\\
\end{array} \right\} \Rightarrow \left\{ \begin{array}{l}{\mathtt{x}} = {\mathtt{0.149\: \!218\: \!940\: \!641\: \!787\: \!8}}\\
{\mathtt{x}} = {\mathtt{3.350\: \!781\: \!059\: \!358\: \!212\: \!2}}\\
\end{array} \right\}$$

And that's it.....!!!!!