TeX Quellcode:

\begin{array}{rclclll}\lg\left(x^2+6x+9\right)-\log_3(81) &=& \lg(x+3) &\vert& +\log_3(81) -\lg(x+3) \\\lg\left((x+3)^2\right)-\lg(x+3) &=& \log_3\left(3^4\right) &\vert& \text{2. Logarithmengesetz} \\\lg\left(\dfrac{(x+3)^2}{x+3}\right) &=& 4 \\\lg(x+3) &=& 4 &\vert& 10^{*} \\10^{\lg(x+3)} &=& 10^4 \\x+3 &=& 10.000 &\vert& -3 \\x &=& 9.997 \;\in\;\mathbb{D} \\ \\\mathbb{L} &=& \{9.997\}\end{array}