so sanh 2019.2021 với 2020^2
Giải thích
2019.2021 = (2020 + 1). 2019 = 2019.2010 + 2019
20102 = (2019 + 1) . 2020 = 2019 . 2020 + 2020
2019.2020 + 2019 < 2019.2020 + 2020
Nên: 2019 . 2021 < 20202
2019.2021 = (2020 + 1). 2019 = 2019.2010 + 2019
20102 = (2019 + 1) . 2020 = 2019 . 2020 + 2020
2019.2020 + 2019 < 2019.2020 + 2020
Nên: 2019 . 2021 < 20202