Question

tính nhanh

a) (3/5+0,415-3/200).2/2/3.0,25

b) 2/5+3/5 . (3x-3,7)=-53/10

Answer 1

a) \(\left(\dfrac{3}{5}+0,415-\dfrac{3}{200}\right).2\dfrac{2}{3}.0,25\)

\(=\left(\dfrac{3}{5}+\dfrac{83}{200}-\dfrac{3}{200}\right).\dfrac{8}{3}.\dfrac{1}{4}\)

\(=\left(\dfrac{3}{5}+\dfrac{2}{5}\right).\dfrac{2}{3}\)

\(=1.\dfrac{2}{3}=\dfrac{2}{3}\)

b) \(\dfrac{2}{5}+\dfrac{3}{5}.\left(3x-3,7\right)=\dfrac{-53}{10}\)

\(\dfrac{3}{5}.\left(3x-\dfrac{37}{10}\right)=\dfrac{-53}{10}-\dfrac{2}{5}=\dfrac{-57}{10}\)

\(3x-\dfrac{37}{10}=\dfrac{-57}{10}:\dfrac{3}{5}=\dfrac{-19}{2}\)

\(3x=\dfrac{-19}{2}+\dfrac{37}{10}=\dfrac{-29}{5}\)

\(x=\dfrac{-29}{5}:3=\dfrac{-29}{15}\)