\(S=5+5^2+5^3+5^4+...+5^{2022}\\ =\left(5+5^2\right)+5^2.\left(5+5^2\right)+...+5^{2020}.\left(5+5^2\right)\\ =30+30.5^2+...+30.5^{2020}\\ =30.\left(1+5^2+...+5^{2020}\right)⋮30\)
\(S=5+5^2+5^3+...+5^{2022}\)
\(\Rightarrow S=\left(5+5^2\right)+5^2\left(5+5^2\right)+...+5^{2000}\left(5+5^2\right)\)
\(\Rightarrow S=20+5^2.20+...+5^{2000}.20\)
\(\Rightarrow S=20\left(1+5^2+...+5^{2000}\right)⋮20\)
\(\Rightarrow dpcm\)
................ = 30(1 + 52 +...+ 52022) ⋮ 30.
=) S ⋮ 30.
ANH ( CHỊ ) POP POP CHO EM HỎI SAO 5^2022 LẠI THÀNH 5^2020 VẬY Ạ??