\(31^{12}=\left(31^3\right)^4=29791^4\left(1\right)\)
\(27^{20}=\left(27^5\right)^4=14348907^4\left(2\right)\)
từ (1) và (2) => 31^12 <27^20
31\(^{12}\)<32\(^{12}\)=(2\(^5\))\(^{12}\)=2\(^{60}\) (1)
27\(^{12}\)=(3\(^3\))\(^{20}\)=3\(^{60}\) (2)
=> 27\(^{20}\)>31\(^{12}\)