a) log_32=a, oblicz log_2 13.5
log_213,5=log_2(\frac{27}{2})=log_227-log_22=
=\frac{log_327}{log_32}-1=\frac{3}{a}-1=\frac{3-a}{a}
c)
log_52=a i log_57=b
{log_{125}28=\frac{log_528}{log_5125}=\frac{log_5(4\cdot7)}{log_55^3}=\frac{log_54+log_57}{3}=\frac{log_52^2+b}{3}=\frac{2log_52+b}{3}=\frac{2a+b}{3}}
Zasatosowane wzory
a) log_ab=\frac{log_cb}{log_ca}
b) log_a(x*y)=log_ax+log_ay