The function $\mathrm{f}$ defined on $\left(-\frac{1}{3}, \frac{1}{3}\right)$ by…
The function $\mathrm{f}$ defined on $\left(-\frac{1}{3}, \frac{1}{3}\right)$ by
$\mathrm{f}(x)=\left\{\begin{array}{cc}
\frac{1}{x} \log \left(\frac{1+3 x}{1-2 x}\right), & x \neq 0 \\
\mathrm{k} & , \quad x=0
\end{array}\right.$
is continuous at $x=0$, then $\mathrm{k}$ is