Giá trị biểu thức \(A=\dfrac{\dfrac{2}{3}-\dfrac{2}{5}+\dfrac{2}{10}}{\dfrac{8}{3}-\dfrac{8}{5}+\dfrac{8}{10}}+\dfrac{1}{2}\) là
\(\dfrac{3}{8}.\)\(\dfrac{5}{9}.\)\(\dfrac{3}{4}.\)\(\dfrac{1}{3}.\)Hướng dẫn giải:\(A=\dfrac{\dfrac{2}{3}-\dfrac{2}{5}+\dfrac{2}{10}}{\dfrac{8}{3}-\dfrac{8}{5}+\dfrac{8}{10}}+\dfrac{1}{2}=\dfrac{\dfrac{2}{3}-\dfrac{2}{5}+\dfrac{2}{10}}{4\left(\dfrac{2}{3}-\dfrac{2}{5}+\dfrac{2}{10}\right)}+\dfrac{1}{2}=\dfrac{1}{4}+\dfrac{1}{2}=\dfrac{3}{4}.\)