a) \(\frac{-5}{2}:\left(\frac{3}{4}-\frac{1}{2}\right)\\ =\frac{-5}{2}:\left(\frac{3}{4}-\frac{2}{4}\right)\\ =\frac{-5}{2}:\frac{1}{4}\\ =\frac{-5}{2}\cdot4=-10\)
b) \(2,8:\left(\frac{1}{5}-3x\right)=1\frac{2}{5}\\ \Rightarrow\frac{14}{5}:\left(\frac{1}{5}-3x\right)=\frac{7}{5}\\ \Rightarrow\frac{1}{5}-3x=\frac{14}{5}:\frac{7}{5}\\ \Rightarrow\frac{1}{5}-3x=\frac{14}{5}\cdot\frac{5}{7}\\ \Rightarrow\frac{1}{5}-3x=2\\ \Rightarrow3x=\frac{1}{5}-2\\ \Rightarrow3x=\frac{-9}{5}\\ \Rightarrow x=\frac{-9}{5}:3\\ \Rightarrow x=\frac{-9}{5\cdot3}=\frac{-3}{5}\)
Vậy \(x=\frac{-3}{5}\)
a) \(-\frac{5}{2}:\left(\frac{3}{4}-\frac{1}{2}\right)\)
= \(-\frac{5}{2}:\left(\frac{6}{8}-\frac{4}{8}\right)\)
= \(-\frac{5}{2}:\frac{2}{8}\)
=\(-\frac{5}{2}.\frac{8}{2}\)
=\(-\frac{40}{4}\)
=\(-10\)
b) \(2,8:\left(\frac{1}{5}-3x\right)=1\frac{2}{5}\)
=> \(\frac{14}{5}:\left(\frac{1}{5}-3x\right)=\frac{7}{5}\)
=> \(\left(\frac{1}{5}-3x\right)=\frac{14}{5}:\frac{7}{5}\)
=> \(\left(\frac{1}{5}-3x\right)=\frac{14}{5}.\frac{5}{7}\)
=> \(\frac{1}{5}-3x=2\)
=> \(3x=\frac{1}{5}-2\)
=> \(3x=-\frac{9}{5}\)
=> \(x=-\frac{9}{5}:3\)
=> \(x=-\frac{3}{5}\)
