Question

2. thực hiện phép tính

a. \(\dfrac{3}{8}.72\dfrac{1}{5}-51\dfrac{1}{5}.\dfrac{3}{8}\)

b.\(25.\left(\dfrac{-1}{5}^{ }\right)^3+\dfrac{1}{5}-2.\left(\dfrac{-1}{2}\right)^2-\dfrac{1}{2}\)

c.\(35\dfrac{1}{6}.\dfrac{-4}{5}-45\dfrac{1}{6}.\dfrac{-1}{5}\)

Answer 1

a: \(=\dfrac{3}{8}\left(72+\dfrac{1}{5}-51-\dfrac{1}{5}\right)=\dfrac{3}{8}\cdot21=\dfrac{63}{8}\)

b: \(=25\cdot\dfrac{-1}{125}+\dfrac{1}{5}-2\cdot\dfrac{1}{4}-\dfrac{1}{2}=-\dfrac{1}{2}-\dfrac{1}{2}=-1\)

c: \(=4\left(35+\dfrac{1}{6}\right)\cdot\dfrac{-1}{5}-\left(45+\dfrac{1}{6}\right)\cdot\dfrac{-1}{5}\)

\(=\dfrac{-1}{5}\left(140+\dfrac{2}{3}-45-\dfrac{1}{6}\right)=-\dfrac{191}{10}\)