Question

Answer 1

\(S_2=9\left(\dfrac{1}{4.5}+\dfrac{1}{5.6}+...+\dfrac{1}{2021.2022}\right)\)

\(=9\left(\dfrac{1}{4}-\dfrac{1}{5}+\dfrac{1}{5}-\dfrac{1}{6}+...+\dfrac{1}{2021}-\dfrac{1}{2022}\right)\)

\(=9\left(\dfrac{1}{4}-\dfrac{1}{2022}\right)\)

\(=\dfrac{3027}{1348}\)