Đáp án:
Giải thích các bước giải:
a)A=2018.2018=2018²
B=2017 .2019
=(2018-1).(2018+1)
=2018.2018 -2018+2018 -1=2018²-1
⇒A>B
b)A=2019.2021=(2020-1).(2020+1)
=2020.2020-2020+2020-1=2020² -1
B=2018.2022=(2020-2).(2020+2)
=2020.2020 +2020.2 - 2020.2 -2.2
=2020²-4
⇒A>B