- Hướng dẫn giải

$P={\log }_{\frac{1}{\sqrt[3]{a}}}\left(\frac{\sqrt[3]{a^2}.\sqrt[4]{a^5}}{\sqrt[5]{a^3}}\right)$

$$\begin{gathered} ={\log }_{a^{\frac{-1}{3}}}\left(a^{\frac{2}{3}+\frac{5}{4}+\frac{3}{5}}\right) \\ ={\log }_{a^{\frac{-1}{3}}}\left(a^{\frac{79}{60}}\right) \\ =\left(-3\right).\frac{79}{60}.{\log }_a\left(a\right)=\frac{-79}{20} \end{gathered}$$

Chọn đáp án B