For a quadratic function $f ( x )$ with leading coefficient 1 and the function
$$g ( x ) = \left\{ \begin{array} { c c }
\frac { 1 } { \ln ( x + 1 ) } & ( x \neq 0 ) \\
8 & ( x = 0 )
\end{array} \right.$$
when the function $f ( x ) g ( x )$ is continuous on the interval $( - 1 , \infty )$, what is the value of $f ( 3 )$? [3 points]\\
(1) 6\\
(2) 9\\
(3) 12\\
(4) 15\\
(5) 18