TeX source:
\begin{array}{rclcl} \mathbb{D} &=& \mathbb{R} \cr \cr 17^s &=& e &\vert& \ln() \cr \ln(17^s) &=& \ln(e) &\vert& \text{3. Logarithmengesetz} \cr s \cdot \ln(17) &=& 1 &\vert& : \ln(17) \cr s &=& \dfrac{1}{\ln(17)} \approx 0{,}35 \cr \cr \mathbb{L} &=& \left\{\dfrac{1}{\ln(17)}\right\} \end{array}