\(75^{20}=45^{10}\cdot5^{30}=45^{10}\cdot125^{10}=5625^{10}=75^{20}\)
\(75^{20}=\left(3.5^2\right)^{20}\)
\(=3^{20}.5^{40}\)
\(=\left(3^2\right)^{10}.5^{10}.5^{10}.5^{20}\)
\(=\left(3^2.5\right)^{10}.5^{30}\)
\(=\left(5.9\right)^{10}.5^{30}\)
\(=45^{10}.5^{30}\)
Vậy \(75^{20}=45^{10}.5^{30}\)