Question

Tính A = 1 + 3 + 3² - 3³ + 3⁴ - ... + 3⁹⁸ - 3⁹⁹ + 3¹⁰⁰

Answer 1

 

A=3 mũ 101-1 phân số2

 

 

 

 

 

Answer 2

\(A=1-3+3^2-3^3+3^4-...-3^{98}-3^{99}+3^{100}\\ 3A=3-3^2+3^3-3^4-...-3^{98}+3^{99}-3^{100}+3^{101}\\ 3A-A=3^{101}-1\\ \Rightarrow A=\dfrac{3^{101}-1}{2}\)