Question

Tính tổng: S = 3 + \(\frac{3}{2}+\frac{3}{2^2}+...+\frac{3}{2^9}\)

Answer 1

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

\(S=\frac{3}{1}.2+\frac{3}{2}.3+....+\frac{3}{8}.9\)

\(S=3-\frac{3}{9}\)

\(S=\frac{27}{9}+\frac{3}{9}\)

\(S=\frac{30}{9}\)
\(<=>S=3\frac{1}{3}\)

Answer 2

S=3+3/2+3/2²+....+3/2⁹

S=3/1.2+3/2.3+...+3/8.9

S=3-3/9=18/3-3/9=12/3