Rút gọn phân số 

- Hướng dẫn giải

Đáp án cần chọn là: C

$\begin{array}{l}\frac{9^{14}{.25}^5{.8}^7}{{18}^{12}{.625}^3{.24}^3}\\ =\frac{{\left(3^2\right)}^{14}.{\left(5^2\right)}^5.{\left(2^3\right)}^7}{{\left({2.3}^2\right)}^{12}.{\left(5^4\right)}^3.{\left(2^3.3\right)}^3}\\ =\frac{3^{28}{.5}^{10}{.2}^{21}}{2^{12}{.3}^{24}{.5}^{12}{.2}^9{.3}^3}\\ =\frac{2^{21}{.3}^{28}{.5}^{10}}{2^{21}{.3}^{27}{.5}^{12}}=\frac{3}{5^2}=\frac{3}{25}\end{array}$