a) \(\dfrac{-3}{4}x-\dfrac{4}{10}=\dfrac{1}{5}\)
\(\dfrac{-3}{4}x=\dfrac{1}{5}+\dfrac{4}{10}=\dfrac{1}{5}+\dfrac{2}{5}=\dfrac{3}{5}\)
\(x=\dfrac{3}{5}:\dfrac{-3}{4}=\dfrac{3}{5}.\dfrac{-4}{3}=\dfrac{3.\left(-4\right)}{5.3}=\dfrac{1.\left(-4\right)}{5.1}=\dfrac{-4}{5}\)
b) \(\left|x-\dfrac{3}{4}\right|:\dfrac{1}{2}+\dfrac{3}{2}=2\dfrac{1}{2}\)
\(\left|x-\dfrac{3}{4}\right|:\dfrac{1}{2}=2\dfrac{1}{2}-\dfrac{3}{2}=\dfrac{5}{2}-\dfrac{3}{2}=\dfrac{2}{2}=1\)
\(\left|x-\dfrac{3}{4}\right|=1.\dfrac{1}{2}=\dfrac{1}{2}\)
\(\Rightarrow x-\dfrac{3}{4}=\dfrac{1}{2}\) hoặc \(x-\dfrac{3}{4}=\dfrac{-1}{2}\)
\(+x-\dfrac{3}{4}=\dfrac{1}{2}\)
\(x=\dfrac{1}{2}+\dfrac{3}{4}=\dfrac{2}{4}+\dfrac{3}{4}=\dfrac{5}{4}\)
\(+x-\dfrac{3}{4}=\dfrac{-1}{2}\)
\(x=\dfrac{-1}{2}+\dfrac{3}{4}=\dfrac{-2}{4}+\dfrac{3}{4}=\dfrac{1}{4}\)
\(\Rightarrow x\in\left\{\dfrac{5}{4};\dfrac{1}{4}\right\}\)
\(\dfrac{-3}{4}x-\dfrac{4}{10}=\dfrac{1}{5}\)
\(\Rightarrow\dfrac{-3}{4}x=\dfrac{1}{5}+\dfrac{4}{10}=\dfrac{3}{5}\)
\(\Rightarrow x=\dfrac{3}{5}.\dfrac{-4}{3}=\dfrac{-4}{5}\)
b, \(\left|x-\dfrac{3}{4}\right|:\dfrac{1}{2}+\dfrac{3}{2}=2\dfrac{1}{2}\)
\(\Rightarrow\left|x-\dfrac{3}{4}\right|:\dfrac{1}{2}=1\Rightarrow\left|x-\dfrac{3}{4}\right|=\dfrac{1}{2}\)
\(\Rightarrow\left[{}\begin{matrix}x-\dfrac{3}{4}=\dfrac{1}{2}\\x-\dfrac{3}{4}=\dfrac{-1}{2}\end{matrix}\right.\Rightarrow\left[{}\begin{matrix}x=\dfrac{5}{4}\\x=\dfrac{1}{4}\end{matrix}\right.\)
