Ta có:
\(\frac{5^5.20^4}{25^5.4^5}=\frac{5^5.5^4.4^4}{5^{10}.4^5}=\frac{5^9.4^4}{5^{10}.4^5}=\frac{1}{5.4}=\frac{1}{20}\)
\(\frac{5^5.20^4}{25^5.4^5}=\frac{5^5.\left(5.2^2\right)^4}{\left(5^2\right)^5.\left(2^2\right)^5}=\frac{5^5.5^4.2^8}{5^{10}.2^{10}}=\frac{5^9.2^8}{5^{10}.2^{10}}=\frac{1}{5.2^2}=\frac{1}{5.4}=\frac{1}{20}.\)
Chúc bạn học tốt!