Question

Thực hiện phép tính ( tính nhanh nếu có thể)

a) \(\dfrac{-7}{25}\). \(\dfrac{11}{13}\)+ \(\dfrac{-7}{25}\). \(\dfrac{2}{13}\)- \(\dfrac{18}{25}\)

b) \(\dfrac{5}{7}\). \(\dfrac{1}{3}\) - \(\dfrac{5}{7}\). \(\dfrac{1}{4}\) - \(\dfrac{5}{7}\). \(\dfrac{1}{12}\)

c) 5\(\dfrac{2}{5}\). 4\(\dfrac{2}{7}\) + 5\(\dfrac{5}{7}\). 5\(\dfrac{2}{5}\)

d) 75% - 1\(\dfrac{1}{2}\) + 0,5 : \(\dfrac{5}{12}\) - \(\left(\dfrac{-1}{2}\right)^2\)

Answer 1

a: \(=\dfrac{-7}{25}\left(\dfrac{11}{13}+\dfrac{2}{13}\right)-\dfrac{18}{25}=\dfrac{-7}{25}-\dfrac{18}{25}=-1\)

c: \(=\dfrac{5}{7}\left(\dfrac{1}{3}-\dfrac{1}{4}-\dfrac{1}{12}\right)=0\)

c: \(=\dfrac{27}{5}\cdot\dfrac{30}{7}+\dfrac{40}{7}\cdot\dfrac{37}{5}\)

\(=\dfrac{27\cdot30+40\cdot37}{35}=\dfrac{458}{7}\)

d: \(=\dfrac{3}{4}-\dfrac{3}{2}+\dfrac{1}{2}\cdot\dfrac{12}{5}-\dfrac{1}{4}\)

\(=\dfrac{1}{2}-\dfrac{3}{2}+\dfrac{6}{5}=-1+\dfrac{6}{5}=\dfrac{1}{5}\)