[tex]\it \log_3 \dfrac{3}{4} = \log_3 4-log_3 3 = \log_3 4-1 \ \ \ \ (*)
\\\;\\ \\\;\\
\log_34 -\log_3 \dfrac{4}{3} \stackrel{(*)}{=} \log_3 4- (\log_34-1) =\log_3 4-\log_34 +1 =1[/tex]
Sau :
[tex]\it log_3 4 -log_3\dfrac{4}{3} =log_3 4:\dfrac{4}{3} =log_34\cdot\dfrac{3}{4} = log_3 3 = 1[/tex]
