Question

[Nguyễn Ngọc Quế Anh]

Câu 1: Tính tổng M= 1 + (- 2) + (- 2)² + . . . + (- 2)²⁰⁰⁶

Answer 1

[Dao Thi Bac]

khong biet

Answer 2

[le bao truc]

Ta có
\(M=1+\left(-2\right)+\left(-2\right)^2+...+\left(-2\right)^{2006}\)
\(M=\left(-2\right)^0+\left(-2\right)^1+\left(-2\right)^2+...+\left(-2\right)^{2006}\)
\(-2M=\left(-2\right)^1+\left(-2\right)^2+\left(-2\right)^3+...+\left(-2\right)^{2007}\)
\(3M=M-\left(-2M\right)=\left(-2\right)^0-\left(-2\right)^{2007}\)
\(\Rightarrow M=\frac{3M}{3}=\frac{1+2^{2007}}{3}\)