[tex]\log_{11}3\cdot\log_75=\frac{\log_73}{\log_711}\cdot\frac{\log_{11}5}{\log_{11}7}=\frac{\log_73\cdot\log_{11}5}{\log_711\cdot\log_{11}7}=\frac{\log_73\cdot\log_{11}5}{\frac{1}{\log_{11}7}\cdot\log_{11}7}=\\=\log_73\cdot\log_{11}5}\\[/tex]
Am folosit:
[tex]\log_aA=\frac{\log_bA}{\log_ba}\\
\log_ba=\frac{1}{\log_ab}[/tex]
