Hiện tại chỉ nghĩ được $5$ cách .
$C1$ .
$\dfrac{2019}{2020} ≈ 0,999504....$
$\dfrac{2024}{2025} ≈ 0,999506....$
$⇒ \dfrac{2019}{2020} < \dfrac{2024}{2025}$
$C2$
$\dfrac{2019}{2020} = \dfrac{2019 \times 2025}{2020 \times 2025}=\dfrac{4078380}{2020 \times 2025}$
$\dfrac{2024}{2025} = \dfrac{2024 \times 2020}{2020 \times 2025}= \dfrac{4088480}{2020 \times 2025}$
Vì : $\dfrac{4088480}{2020 \times 2025} > \dfrac{4078380}{2020 \times 2025}$
$⇒ \dfrac{2019}{2020} < \dfrac{2024}{2025}$
$C3$.
$\dfrac{2019}{2020} - \dfrac{2024}{2025} = \dfrac{2025 \times 2019 - 2020 \times 2024}{2020 \times 2025} = \dfrac{-5}{2020 \times 2025}$ là số âm nên $\dfrac{2019}{2020} < \dfrac{2024}{2025}$
$⇒$ $\dfrac{2019}{2020} < \dfrac{2024}{2025}$
$C4$.
$\dfrac{2024}{2025} - \dfrac{2019}{2020} = \dfrac{2020 \times 2024 - 2025 \times 2019}{2020 \times 2025} = \dfrac{5}{2020 \times 2025}$ là số dương nên $\dfrac{2019}{2020} < \dfrac{2024}{2025}$
$⇒$ $\dfrac{2019}{2020} < \dfrac{2024}{2025}$
$C5$. $\dfrac{2019}{2020} = 1 - \dfrac{1}{2020}$
$\dfrac{2024}{2025} = 1- \dfrac{1}{2025}$
Vì : $\dfrac{1}{2020} > \dfrac{1}{2025}$
$⇒$ $\dfrac{2019}{2020} < \dfrac{2024}{2025}$
