Question

Answer 1

\(=\dfrac{1}{2}-\dfrac{1}{3}+\dfrac{1}{3}-\dfrac{1}{4}+...+\dfrac{1}{9}-\dfrac{1}{10}=\dfrac{1}{2}-\dfrac{1}{10}=\dfrac{4}{10}=\dfrac{2}{5}\)

Answer 2

b: \(=\left(\dfrac{1}{7}+\dfrac{6}{7}\right)+\left(\dfrac{2}{9}+\dfrac{7}{9}\right)+\left(\dfrac{3}{10}+\dfrac{7}{10}\right)=3\)