TeX source:
\begin{array}{rclcl} \mathbb{D} &=& \mathbb{R} \cr \cr 10^x &=& 100^{x+1} \cr 10^x &=& \left(10^2\right)^{x+1} &\vert& \text{5. Potenzgesetz} \cr 10^x &=& 10^{2(x+1)} &\vert& \lg() \cr \lg\left(10^x\right) &=& \lg\left(10^{2(x+1)}\right) \cr x &=& 2(x+1) \cr x &=& 2x+2 &\vert& -2x \cr -x &=& 2 &\vert& \cdot (-1) \cr x &=& -2 \cr \cr \mathbb{L} &=& \{-2\} \end{array}