So sánh a = 2525/2626 với b = 20212021/20222022

Hướng dẫn giải:

Đáp án đúng là: C

+) Ta có: \(a = \frac{{2525}}{{2626}} = \frac{{25.101}}{{26.101}} = \frac{{25}}{{26}}\)

Suy ra \(1 - a = 1 - \frac{{25}}{{26}} = \frac{1}{{26}}\);

Ta có: \[b = \frac{{20212021}}{{20222022}} = \frac{{2021.10001}}{{2022.10001}} = \frac{{2021}}{{2022}}\]

Suy ra \[1 - b = 1 - \frac{{2021}}{{2022}} = \frac{1}{{2022}}\]

Vì 26 < 2022 nên \(\frac{1}{{26}} > \frac{1}{{2022}}\) hay 1 – a > 1 – b

Do đó a < b.