TeX Quellcode:

\begin{array}{ccl} \log_a(2x)-\log_a(4)+\log_a\left(\dfrac{2}{x}\right) &=& \log_a\left(\dfrac{2x\cdot 2}{4 \cdot x}\right) \cr &=& \log_a(1) \cr &=& 0 \end{array}