1) \(\dfrac{3}{8}-\dfrac{4}{5}-\dfrac{-17}{40}=\dfrac{15}{40}-\dfrac{32}{40}-\dfrac{-17}{40}=\dfrac{-17}{40}-\dfrac{-17}{40}=\dfrac{34}{40}=\dfrac{17}{20}\)
2) \(\dfrac{3}{4}-\dfrac{16}{32}+\dfrac{4}{-3}=\dfrac{3}{4}-\dfrac{1}{2}+\dfrac{-4}{3}=\dfrac{9}{12}-\dfrac{6}{12}+\dfrac{-16}{12}=\dfrac{-13}{12}\)
3) \(\dfrac{-4}{7}+\dfrac{2}{3}.\dfrac{-9}{14}=\dfrac{-4}{7}+\dfrac{-3}{7}=-1\)
4) \(8\dfrac{2}{7}-\left(3\dfrac{4}{9}+4\dfrac{2}{7}\right)=\dfrac{58}{7}-\left(\dfrac{31}{9}+\dfrac{30}{7}\right)=\dfrac{58}{7}-\dfrac{31}{9}-\dfrac{30}{7}=\dfrac{58}{7}-\dfrac{30}{7}-\dfrac{31}{9}=\dfrac{28}{7}-\dfrac{31}{9}=4-\dfrac{31}{9}=\dfrac{36}{9}-\dfrac{31}{9}=\dfrac{5}{9}\)
5)
\(\left(\dfrac{2}{3}-1\dfrac{1}{2}\right):\dfrac{4}{3}+\dfrac{1}{2}=\left(\dfrac{2}{3}-\dfrac{3}{2}\right):\dfrac{4}{3}+\dfrac{1}{2}=\left(\dfrac{4}{6}-\dfrac{9}{6}\right):\dfrac{4}{3}+\dfrac{1}{2}=\dfrac{-5}{6}:\dfrac{4}{3}+\dfrac{1}{2}=\dfrac{-5}{6}.\dfrac{3}{4}+\dfrac{1}{2}=\dfrac{-5}{8}+\dfrac{1}{2}=\dfrac{-5}{8}+\dfrac{4}{8}=\dfrac{-1}{8}\)
6, \(\dfrac{-5}{13}+\dfrac{2}{5}+\dfrac{-8}{13}+\dfrac{3}{5}-\dfrac{3}{7}=\left(\dfrac{-5}{13}+\dfrac{-8}{13}\right)+\left(\dfrac{2}{5}+\dfrac{3}{5}\right)=-1+1=0\)
Đây là câu 6
