Ta thấy:

\(11^{1979}< 11^{1980}\)

\(11^{1980}=\left(11^3\right)^{660}=1331^{660}\)

Và:

\(37^{1320}=\left(37^2\right)^{660}=1369^{660}\)

Mà: \(1331^{660}< 1369^{660}\)

\(\Rightarrow11^{1979}< 37^{1320}\)

11^1979 và 37^1320 

11^1979 < 12.1979 = (3.2.2)^1979 = 2^1979.6^1979 
37^1320 > 36^1320 = (6^2)^1320 = 6^2640 = 6^661.6^1979 

\(^{11^{1979}}

11¹⁹⁷⁹ < 37¹³²⁰

11^1979 < 12.1979 = (3.2.2)^1979 = 2^1979.6^1979 
37^1320 > 36^1320 = (6^2)^1320 = 6^2640 = 6^661.6^1979 

a)2^31=2.2^30=2.8^10

3^21=3.3^20=3.9^10

Vì 2.8^10<3.^10

\(\Rightarrow\)28^10<3.9^10\(\Rightarrow\)2^31<3^21

b)3^39=3^\(^{13x3}\)=159323^3

11^21=11\(^{7x3}\)=19487171^3

Vì 159323^3<19487171^3\(\Rightarrow\)3^39<11^21

c)11^1979<37^1320=(11^3)^660=1331^660

37^1320=(37^2)^660\(\Rightarrow\)11^1979<37^1320