Question

A=1/3.41 + 1/4.42 + 1/5.43 +...+ 1/33.71

B=1/3.34 + 1/4.35 + 1/5.36 +...+ 1/46.71

Tính A/B

Answer 1

\(A=\frac{1}{3.41}+\frac{1}{4.42}+...+\frac{1}{33.71}\)

\(\Leftrightarrow A=\frac{1}{38}\left(\frac{1}{3}-\frac{1}{41}+\frac{1}{4}-\frac{1}{42}+...+\frac{1}{33}-\frac{1}{71}\right)\)

\(B=\frac{1}{3.34}+\frac{1}{4.35}+...+\frac{1}{46.71}\)

\(\Leftrightarrow B=\frac{1}{31}\left(\frac{1}{3}-\frac{1}{34}+\frac{1}{4}-\frac{1}{35}+...+\frac{1}{46}-\frac{1}{71}\right)\)

​\(\Leftrightarrow B=\frac{1}{31}\left(\frac{1}{3}-\frac{1}{41}+\frac{1}{4}-\frac{1}{42}+...+\frac{1}{33}-\frac{1}{71}\right)\)​

\(\Leftrightarrow\frac{A}{B}=\frac{31}{38}\)