A=2020.2022
=2020.(2021+1)
=2020.2021+2020
B=2021.2021
=2021.(2020+1)
=2021.2020+2021
Mà 2020.2021+2020 < 2021.2020+2021
Nên A < B
11111111 - 2222
=(11110000+1111)-2.1111
=1111(10000+1)-2.1111
=1111(10000+1-2)
=1111.9999
=1111.9.1111
=1111.3.3.1111
=3333.3333
2.Ta có :
A= 2021 . 2021
A = 2021 . ( 2022 - 1 )
A = 2021 . 2022 - 2021 . 1
A = 2021 . 2022 - 2021
Ta lại có :
B = 2020 . 2022
B = ( 2021 - 1 ) . 2022
B = 2022 . 2021 - 2022 . 1
B = 2022 . 2021 - 2022
Ta thấy : 2021 . 2022 - 2021 > 2022 . 2021 - 2022
=> A > B