Limits Continuity And Differentiability

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