a) \(0,75:4,5=\dfrac{1}{5}:\left(2y\right)\)
\(\Rightarrow\dfrac{3}{4}.\dfrac{1}{4,5}=\dfrac{1}{5}:\left(2y\right)\)
\(\Rightarrow\dfrac{1}{6}=\dfrac{1}{5}:\left(2y\right)\)
\(\Rightarrow2y=\dfrac{1}{5}:\dfrac{1}{6}\)
\(\Rightarrow2y=\dfrac{1}{5}.\dfrac{6}{1}\)
\(\Rightarrow2y=\dfrac{6}{5}\)
\(\Rightarrow y=\dfrac{6}{5}:2\)
\(\Rightarrow y=\dfrac{6}{5}.\dfrac{1}{2}\)
\(\Rightarrow y=\dfrac{6}{10}\)
\(\Rightarrow y=\dfrac{3}{5}\)
Vậy \(y=\dfrac{3}{5}\)
b) \(\left|y-4\right|-12=2y\)
\(\Leftrightarrow\left|y-4\right|=2y+12\)
Xét trường hợp 1: \(y-4=2y+12\)
\(\Rightarrow y-4-\left(2y+12\right)=0\)
\(\Rightarrow y-4-2y-12=0\)
\(\Rightarrow-16-y=0\)
\(\Rightarrow y=-16\)
Xét trường hợp 2: \(y-4=-\left(2y+12\right)\)
\(\Rightarrow y-4-\left[-\left(2y+12\right)\right]=0\)
\(\Rightarrow y-4+2y+12=0\)
\(\Rightarrow8+3y=0\)
\(\Rightarrow3y=-8\)
\(\Rightarrow y=\dfrac{-8}{3}\)
Vậy \(y=-16\) hoặc \(y=\dfrac{-8}{3}\)
