Ta có : 5566 = [(11.5)6]11 = (116 . 56)11 = (115 . 11 . 56)11
6655 = [(11.6)5]11 = (115 . 65)11
Vì 11 . 56 > 65 nên 5566 > 6655
\(55^{66}=\left(55^6\right)^{11}=\left[\left(11.5\right)^6\right]^{11}=\left(11^6.5^6\right)^{11}=\left(11^5.11.5^6\right)^{11}\)
\(66^{55}=\left(66^5\right)^{11}=\left[\left(11.6\right)^5\right]^{11}=\left(11^5.6^5\right)^{11}\)
Vì : \(11.5^6>6^5\)
Vậy : \(55^{66}>66^{55}\)