TeX source:

\mathbf{D}\left(\log _{\pi}\left(\mathrm{e}^{\mathrm{x}}\right)\right)=\frac{1}{\mathrm{e}^{\mathrm{x}} \cdot \ln (\pi)} \mathrm{D}\left(\mathrm{e}^{\mathrm{x}}\right)=\frac{\mathbf{e}^{\mathbf{x}}}{\mathrm{e}^{\mathrm{x}} \cdot \ln (\pi)}=\frac{1}{\ln (\pi)}