Вычислите $$\frac{\left(log_613\right)^2-2log_613log_639+(log_639)^2}{\left(log_681\right)^2}$$

$$\frac{\left(log_613\right)^2-2log_613log_639+(log_639)^2}{\left(log_681\right)^2}$$$$=\frac{\left(\log_613-\log_639\right)^2}{\left(\log_681\right)^2}=\frac{\left(\log_6\frac13\right)^2}{\left(4\cdot\log_63\right)^2}=\frac1{16}=0,0625$$
0,0625