Question

= 5 + 5 mũ 2 + 5 mũ 3 + ... + 5 mũ 2021 cho 30

Answer 1

\(A=5+5^2+5^3+...+5^{2021}\)

\(\Rightarrow A=\left(5^1+5^2\right)+5^2\left(5^1+5^2\right)...+5^{2018}\left(5^1+5^2\right)+5^{2021}\)

\(\Rightarrow A=30+5^2.30...+5^{2018}.30+5^{2021}\)

\(\Rightarrow A:30=1+5^2+...+5^{2018}+\dfrac{5^{2021}}{30}\)

\(\Rightarrow A:30=1+5^2+...+5^{2018}+\dfrac{5^{2020}}{6}\)

Answer 2

số dư là bao nhieu ạ ?

đề bài tìm số dư ạ 

Answer 3

Số dư là \(\dfrac{5^{2020}}{6}\)