339= 313.3=(313)3= 15943233
1121=117.3= (117)3= 194871713
Vì: 15943233<194871713 (1594323<19487171)
=> 339<1121
Ta có: 339 = (313)3 = 15943233
1121 = (117)3 = 194871713
Ta lại có 15943233<194871713
Hay 339 < 1121
Vậy 339<1121
Ta có \(3^{39}=\left(3^{13}\right)^3=1594323^3\)
\(11^{21}=\left(11^7\right)^3=19487171^3\)
Vì \(1594323^3< 19487171^3\) nên \(3^{39}< 11^{21}\)
Vậy :\(3^{39}< 11^{21}\)