Cho -2020a > -2020b. Khi đó? a < b

* Hướng dẫn giải

Đáp án A

Ta có: -2020a > -2020b

$$\begin{gathered} \iff -2020. \left(-\frac{\text{1}}{\text{2020}}\right)a < -2020.\left(-\frac{\text{1}}{\text{2020}}\right)b \\ \iff a < b \end{gathered}$$