so sánh 2 phân số 2020^2019 +1 / 2020^2020 – 1 và 2020^2018+1 / 2020^2019 -1

Đặt M = 2020^2019+1/2020^2020-1

=> 2020M = 2020^2020+2020/2020^2020-1 = 2020^2020-1+2021/2020^2020-1 = 1 + 2021/2020^2020-1

Đặt N = 2020^2018+1/2020^2019-1

=> 2020N = 2020^2019+2020/2020^2019-1 = 2020^2019-1+2021/2020^2019-1 = 1 + 2021/2020^2019-1

Vì 2021/2020^2020-1 < 2021/2020^2019-1 nên 1 + 2021/2020^2020-1 < 1 + 2021/2020^2019-1

=> 2020M > 2020N

hay M > N

Vậy M > N.

HỌC TỐT!