b=2018.2022=(2020-2)(2020+2)=2020.2020+2.2020-2.2020-4=2020.2020-4<2020.2020
nên a>b
\(A=2020.2020=2020^2\)
\(B=\left(2020+2\right).\left(2020-2\right)=2020^2-2^2\)
Mà 20202 và 22 không âm nên
\(A>B\)
Ta có: \(a=2020.2020=\left(2018+2\right).2020=2018.2020+2020.2\)
\(b=2018.2020=2018.\left(2020+2\right)=2018.2020+2018.2\)
Vì \(2018.2020=2018.2020\)
Mà \(2020.2>2018.2\)
Nên \(2018.2020+2020.2>2018.2020+2018.2\)
Vậy \(a>b\)
mk đông ý vs ý kiến của bạn Hồ Khánh Châu
Ta có : A = 2020.2020 = 2020.(2018+2) = 2020.2018+2020.2
B = 2018.2022 = 2018.(2020+2) = 2018.2020+2018.2
Vì 2020.2018 = 2018.2020 và 2020.2 > 2018.2
=> 2020.2020 > 2018.2022 => A > B