$$\left. \begin{array} { l } { f ( m ) = \frac { 27 - 2 } { 27 x - 1 } g ( x ) = \frac { 1 } { 7 } } \\ { f ^ { \prime } ( m ) = ( g ) = ( 2 x ) , ) , \text { f o r d e \right.$$
$\left\{\begin{matrix}x=-\frac{fm}{25g-27fm}\text{, }&\left(m=0\text{ or }f=0\text{ or }f\neq \frac{25g}{27m}\right)\text{ and }\left(m=0\text{ or }f=0\text{ or }g\neq \frac{27fm}{25}\right)\text{ and }g\neq 0\\x\neq \frac{1}{27}\text{, }&\left(f=0\text{ or }m=0\right)\text{ and }g=0\end{matrix}\right.$
