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\(A=2021^3=2021\cdot2021^2>2021\left(2021^2-1\right)=2021\left(2021\cdot2021-2021+2021-1\right)=2021\cdot\left(2021+1\right)\left(2021-1\right)=2021\cdot2022\cdot2020=B\)
\(B=2020.2021.2022=\left(2021-1\right).2021.\left(2021+1\right)=\left[\left(2021-1\right)\left(2021+1\right)\right].2021=\left(2021^2-2021+2021-1\right).2021=\left(2021^2-1\right).2021=2021^3-2021< 2021^3=A\)
vậy B<A
\(B=2020.2021.2022\\ B=\left(2021-1\right).2021.\left(2021+1\right)\\ B=\left(2021^2-1\right).2021\\ B=2021^3-2021\\ \Rightarrow A>B\)
Tham khảo:https://hoc24.vn/cau-hoi/cho-a-20213-va-b-202020212022-khong-tinh-cu-the-cac-gia-tri-cua-a-va-b-hay-so-sanh-a-va-b-ai-lam-giup-mik-voi.3007463332171
\(A>\left(2021^2-1\right)\cdot2021=\left(2021-1\right)\left(2021+1\right)\cdot2021=B\)
B = 2020.2021.2022
B = (2021 - 1).(2021 + 1).2021
B = (2021.2021 + 2021 - 2021 - 1).2021
B = (20212021-1).2021
B = 20213 - 2021
Vậy A > B
2020.2022=(2021−1)(2021+1)=20212−1<\(2021^2\)
\(\Rightarrow2020.2021.2022< 2021^2.2021=2021^3\)
\(B=\left(2021-1\right)\left(2021+1\right).2021=\left(2021^2-1\right).2021=2021^3-2021< A\)
A=20213=2021⋅20212>2021(20212−1)=2021(2021⋅2021−2021+2021−1)=2021⋅(2021+1)(2021−1)=2021⋅2022⋅2020=B
HT
Vậy \(A< B\)
A= 20213= 2021.2021.2021
=2021.[ 2021.(2020+1)]
=2021.(2020.2021+2021)
B=2020.2021.2022
=2021.(2020.2022)
=2021.[2020.(2021+1)]
=2021.(2020.2021+2020)