$$MCM=6x+12.9x-9.2 { x }^{ 2 } -4x+2$$
$\left\{\begin{matrix}C=-\frac{92x^{2}-149x-20}{10M^{2}}\text{, }&M\neq 0\\C\in \mathrm{C}\text{, }&\left(x=\frac{149-\sqrt{29561}}{184}\text{ or }x=\frac{\sqrt{29561}+149}{184}\right)\text{ and }M=0\end{matrix}\right.$
$\left\{\begin{matrix}C=-\frac{92x^{2}-149x-20}{10M^{2}}\text{, }&M\neq 0\\C\in \mathrm{R}\text{, }&\left(x=\frac{149-\sqrt{29561}}{184}\text{ or }x=\frac{\sqrt{29561}+149}{184}\right)\text{ and }M=0\end{matrix}\right.$
$\left\{\begin{matrix}M=-\frac{iC^{-0.5}\sqrt{920x^{2}-1490x-200}}{10}\text{; }M=\frac{iC^{-0.5}\sqrt{920x^{2}-1490x-200}}{10}\text{, }&C\neq 0\\M\in \mathrm{C}\text{, }&\left(x=\frac{149-\sqrt{29561}}{184}\text{ or }x=\frac{\sqrt{29561}+149}{184}\right)\text{ and }C=0\end{matrix}\right.$
$\left\{\begin{matrix}M=\frac{\sqrt{-\frac{10\left(92x^{2}-149x-20\right)}{C}}}{10}\text{; }M=-\frac{\sqrt{-\frac{10\left(92x^{2}-149x-20\right)}{C}}}{10}\text{, }&\left(C>0\text{ or }x\leq \frac{149-\sqrt{29561}}{184}\text{ or }x\geq \frac{\sqrt{29561}+149}{184}\right)\text{ and }\left(x\geq \frac{149-\sqrt{29561}}{184}\text{ or }C<0\right)\text{ and }C\neq 0\text{ and }\left(x\leq \frac{\sqrt{29561}+149}{184}\text{ or }C<0\right)\\M\in \mathrm{R}\text{, }&\left(x=\frac{149-\sqrt{29561}}{184}\text{ or }x=\frac{\sqrt{29561}+149}{184}\right)\text{ and }C=0\end{matrix}\right.$