Ta có :
\(75^{10}.75^{10}=\left(5^{10}.3^{10}.3^{10}\right).\left(5^{10}.5^{10}.5^{10}\right)\)
\(75^{10}.75^{10}=\left(5^{10}.5^{10}.3^{10}\right).\left(5^{10}.5^{10}.3^{10}\right)\)
\(75^{10}.75^{10}=75^{10}.75^{10}\)
Vì vậy : \(75^{20}=45^{10}.5^{30}\)
\(75^{20}=3^{20}.5^{40}\)
\(45^{10}.5^{30}=3^{20}.5^{40}\)
Do đó:\(75^{20}=45^{10}.5^{30}\)(đpcm)