Xét A = 20172018 - 20172017
=> 2017A = 20172019 - 20172018
Ta thấy B = 2017A
Mà 2017A>A=>B>A
ta có
A=2017^2017 . 2017 - 2017^2017
=2017^2017.(2017-1)
B=2017^2018.2017 - 2017^2018
=2017^2018 .(2017-1)
Vi
2017^2017<2017^2018
=>2017^2017.(2017-1)<2017^2018.(2017-1)
=>A<B