log_35*log_{25}81
źródło:
log_3*log_{25}81=\frac{log_{25}5}{log_{25}3}*log_{25}3^4=
=\frac{log_{25}5*4log_{25}3}{log_{25}3}=4log_{25}5=
4*\frac{log_55}{log_525}=4*\frac{1}{2}=2