Đặt a = log23, b = log35. Hã...

D

- Hướng dẫn giải

\(\begin{array}{*{20}{l}}
\begin{array}{l}
P = 1 + {\log _{60}}10 = 1 + \frac{{{{\log }_2}10}}{{{{\log }_2}6}}\\
 = 1 + \frac{{1 + {{\log }_2}5}}{{1 + {{\log }_2}3}}
\end{array}\\
\begin{array}{l}
 = 1 + \frac{{1 + {{\log }_2}3.{{\log }_3}5}}{{1 + {{\log }_2}3}}\\
 = 1 + \frac{{1 + ab}}{{1 + a}} = \frac{{2 + a + ab}}{{1 + a}}
\end{array}
\end{array}\)