Question

tính

A=1+3+3^2+3^3+.....3^100

Answer 1

A=1+3+3²+...+3¹⁰⁰

3A=3(1+3+3²+...+3¹⁰⁰)

3A=3+3²+...+3¹⁰¹

3A-A=(3+3²+...+3¹⁰¹)-(1+3+3²+...+3¹⁰⁰)

2A=3¹⁰¹-1

\(A=\frac{3^{101}-1}{2}\)

Answer 2

\(A=1+3+3^2+3^3+...+3^{100}\)

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

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

\(=>A=3^{101}-1\)

Answer 3

MÌnh nhầm !! xin lỗi bạn !! bạn thắng làm đúng rồi nhé !!!