Ta có :
\(2^{70}=\left(2^7\right)^{10}=128^{10}\)
\(7^{20}=\left(7^2\right)^{10}=49^{10}\)
Vì 128 > 49 nên \(128^{10}>49^{10}\)
Vậy \(2^{70}>7^{20}\) .
\(2^{70}=14^{10}\)
\(7^{20}=7^{10}.7^{10}\)
\(\Rightarrow2^{70}>7^{20}\)
\(2^{70}=2^{7.10}=\left(2^7\right)^{10}=128^{10}\)
\(7^{20}=7^{2.10}=\left(7^2\right)^{10}=49^{10}\)
\(128>49\Rightarrow128^{10}>49^{10}\Rightarrow2^{70}>7^{20}\)