Question

[Trần Anh Trang]

Tính tổng

B=3-3 mu 2 +3 mu 3 -......- 3 mu 100

A=1+2+ 2 mu 2 +......+2 mu 100

Answer 1

[Nhung Mun]

\(A=1+2+2^2+...+2^{100}\)

\(2A=2+2^2+2^3+..,+2^{101}\)

\(2A-A=\left(2+2^2+2^3+...+2^{101}\right)-\left(1+2+2^2+...+2^{100}\right)\)

\(A=2^{101}-1\)

\(B=\)\(3-3^2+3^3-...-3^{100}\)