Question

B=17/10+17/40+17/88+17/154+17/238

Answer 1

\(B=\frac{17}{10}+\frac{17}{40}+\frac{17}{188}+\frac{17}{154}+\frac{17}{238}\)

\(B=\frac{17}{2.5}+\frac{17}{8.5}+\frac{17}{11.8}+\frac{17}{11.14}+\frac{17}{14.17}\)

\(\frac{3}{17}B=\frac{3}{2.5}+\frac{3}{8.5}+\frac{3}{11.8}+\frac{3}{11.14}+\frac{3}{14.17}\)

\(\frac{3}{17}B=\frac{1}{2}-\frac{1}{5}+\frac{1}{5}-\frac{1}{8}+...+\frac{1}{14}-\frac{1}{17}\)

\(\frac{3}{17}B=\frac{1}{2}-\frac{1}{17}=\frac{17}{34}-\frac{2}{34}=\frac{15}{34}\)

\(B=\frac{15}{34}:\frac{3}{17}=\frac{15}{34}.\frac{17}{3}=\frac{5}{2}\)

Học tốt!!!