a, Ta có : \(119^{20}=\left(119^4\right)^5=200533921^5\)
\(2003^{15}=\left(2003^3\right)^5=8036054027^5\)
Vì \(200533921< 8036054027\)nên \(200533921^5< 8036054027^5\)
hay \(119^{20}< 2003^{15}\)
Vậy \(119^{20}< 2003^{15}\)
b, Ta có : \(3^{39}=\left(3^{13}\right)^3=1594323^3\)
\(11^{21}=\left(11^7\right)^3=19487171^3\)
Vì \(1594323< 19487171\)nên \(1594323^3< 19487171^3\)
hay \(3^{39}< 11^{21}\)
Vậy \(3^{39}< 11^{21}\)