Question

A=\(\frac{2}{3.5}+\frac{2}{5.7}+.....+\frac{2}{11.113}\)

Giúp mình nhé !

Answer 1

\(A=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{111}-\frac{1}{113}\)

\(A=\frac{1}{3}-\frac{1}{113}\)

Answer 2

\(A=\frac{2}{3\cdot5}+\frac{2}{5\cdot7}+......+\frac{2}{11\cdot113}\)

\(A=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{11}-\frac{1}{113}\)

\(A=\frac{1}{3}-\frac{1}{113}\)

\(A=\frac{110}{339}\)