Question

[Erza Scarlet]

Tìm số dư khi A chia cho 7 biết

A+1+2+2²+.....+2²⁰⁰¹+2²⁰⁰²

Answer 1

[o0o I am a studious person o0o]

\(A=1+2+2^2+....+2^{2002}\)

\(\Rightarrow A=2A-A=1-2^{2003}\)

\(\Rightarrow A:7=1-2^{2003}:7\)dư 7