\(\text{a) }\text{Vì }\hept{\begin{cases}\text{2020 ⋮ 2}\\\text{2022 ⋮ 2}\end{cases}\Rightarrow\text{2020 + 2022 ⋮ 2}}\)
\(\text{b) Vì }\hept{\begin{cases}\text{2021}^3 ⁒2\\2020^{\text{3}}⋮ 2\end{cases}}\Rightarrow\text{2021}^3-2020^{\text{3}}⁒2\)
Vì 2021 ko chia hết cho2.
2020chia hết cho 2 nên(2021+2020) ko chia hết cho 2