Question

tính tổng: S=3+3/2+3/2²+....+3/2⁹

Answer 1

\(2S=\left(3+\frac{3}{2}+...+\frac{3}{2^9}\right)\)

\(2S=6+3+...+\frac{3}{2^8}\)

\(2S-S=\left(6+3+...+\frac{3}{2^8}\right)-\left(3+\frac{3}{2}+\frac{3}{2^2}+...+\frac{3}{2^9}\right)\)

\(S=6-\frac{3}{2^9}\)

Answer 2

\(2S=\left(3+\frac{3}{2}+...+\frac{3}{2^9}\right)\)

\(2S=6+3+...+\frac{3}{2^8}\)

\(2S-S=\left(6+3+...+\frac{3}{2^8}\right)-\left(3+\frac{3}{2}+\frac{3}{2^2}+...+\frac{3}{2^9}\right)\)

\(S=6-\frac{3}{2^9}\)