\(=\dfrac{5}{8}\left(\dfrac{8}{2\times6\times10}+\dfrac{8}{6\times10\times14}+...+\dfrac{8}{18\times22\times26}\right)\\ =\dfrac{5}{8}\left(\dfrac{1}{2\times6}-\dfrac{1}{6\times10}+\dfrac{1}{6\times10}-\dfrac{1}{10\times14}+...+\dfrac{1}{18\times22}-\dfrac{1}{22\times26}\right)\)
\(=\dfrac{5}{8}\left(\dfrac{1}{2\times6}-\dfrac{1}{22\times26}\right)=\dfrac{5}{8}\left(\dfrac{1}{12}-\dfrac{1}{572}\right)\\ =\dfrac{5}{8}\times\dfrac{35}{429}=\dfrac{175}{3432}\)
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