Question

\(C=\frac{2}{3\times5}+\frac{2}{5\times7}+\frac{2}{7\times9}+...+\frac{2}{97\times99}\)

Answer 1

lộn:

\(C=\frac{1}{3}-\frac{1}{99}\)

\(C=\frac{32}{99}\)

Answer 2

\(C=\frac{2}{3x5}+\frac{2}{5x7}+\frac{2}{7x9}+...+\frac{2}{97x99}\)

\(C=\frac{1}{3}-\frac{1}{5}+\frac{1}{5}-\frac{1}{7}+...+\frac{1}{97}-\frac{1}{99}\)

\(C=\frac{1}{3}-\frac{1}{97}\)

\(C=\frac{94}{291}\)