a) Ta có: \(x:0.75=\dfrac{-1}{12}\)
\(\Leftrightarrow x:\dfrac{3}{4}=\dfrac{-1}{12}\)
hay \(x=-\dfrac{1}{12}\cdot\dfrac{3}{4}=\dfrac{-1}{16}\)
b) Ta có: \(4\dfrac{2}{3}:x=\dfrac{-7}{9}\)
\(\Leftrightarrow\dfrac{14}{3}:x=\dfrac{-7}{9}\)
hay \(x=\dfrac{14}{3}:\dfrac{-7}{9}=\dfrac{14}{3}\cdot\dfrac{-9}{7}=-6\)
q) Ta có: \(\left(x-\dfrac{3}{5}\right)\left(3-x\right)=0\)
\(\Leftrightarrow\left[{}\begin{matrix}x-\dfrac{3}{5}=0\\3-x=0\end{matrix}\right.\Leftrightarrow\left[{}\begin{matrix}x=\dfrac{3}{5}\\x=3\end{matrix}\right.\)