Question

tính tổng S = \(1-3+3^2-3^3+....+3^{101}-3^{102}\)

Answer 1

S=1-3+3^2-3^3+...+3^101-3^102

3S=3-3^2+3^3-3^4+...+3^102-3^103

3S+S=3-3^2+3^3-3^4+...+3^102-3^103+1-3+3^2-3^3+...+3^101-3^102

4S=-3^103+1

S=(-3^103+1):4

Answer 2

S=(1-3¹⁰²)/4

Tick nhé

Answer 3

3S=3-3²+3³-3⁴+....+3¹⁰²-3¹⁰³

3S+S=1-3¹⁰³

4S=1-3¹⁰³

S=(1-3¹⁰³)/4

Tick nhé