Cho a+2020/a-2020 = b+2019/b-2019 . Chứng minh a/b = 2020/2019 . Giúp với ạ đang cần gấp =‹

 Ta có : $\dfrac{a+2020}{a-2020} = \dfrac{b+2019}{b-2019}$

$\to (a+2020).(b-2019) = (a-2020).(b+2019)$

$\to ab – 2019a + 2020b-2020.2019 = ab+2019a-2020b-2020.2019$

$\to 2019a = 2020b$

$\to \dfrac{a}{b} = \dfrac{2020}{2019}$