a: =>|x-4/5|=1/4
=>x-4/5=1/4 hoặc x-4/5=-1/4
=>x=1,05 hoặc x=0,55
b: =>|x+1/2|=1/3
=>x+1/2=1/3 hoặc x+1/2=-1/3
=>x=-1/6 hoặc x=-5/6
a) \(\dfrac{-3}{4}-\left|\dfrac{4}{5}-x\right|=-1\)
\(\left|\dfrac{4}{5}-x\right|=\dfrac{-3}{4}-\left(-1\right)\)
\(\left|\dfrac{4}{5}-x\right|=\dfrac{1}{4}\)
`=>`\(\left[{}\begin{matrix}\dfrac{4}{5}-x=\dfrac{1}{4}\\\dfrac{4}{5}-x=-\dfrac{1}{4}\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=\dfrac{4}{5}-\dfrac{1}{4}=\dfrac{11}{20}\\x=\dfrac{4}{5}-\left(-\dfrac{1}{4}\right)=\dfrac{21}{20}\end{matrix}\right.\)
`=>`\(x=\left\{\dfrac{11}{20};\dfrac{21}{20}\right\}\)
b) \(\left|\dfrac{-1}{2}-x\right|=\dfrac{1}{3}\)
`=>`\(\left[{}\begin{matrix}\dfrac{-1}{2}-x=\dfrac{1}{3}\\\dfrac{-1}{2}-x=-\dfrac{1}{3}\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=\dfrac{-1}{2}-\dfrac{1}{3}=-\dfrac{5}{6}\\x=\dfrac{-1}{2}-\left(-\dfrac{1}{3}\right)=-\dfrac{1}{6}\end{matrix}\right.\)
`=>`\(x=\left\{-\dfrac{5}{6};-\dfrac{1}{6}\right\}\)
c) \(\left|2\dfrac{1}{2}+x\right|-\dfrac{-2}{3}=3\)
\(\left|\dfrac{5}{2}+x\right|+\dfrac{2}{3}=3\)
\(\left|\dfrac{5}{2}+x\right|=3-\dfrac{2}{3}\)
\(\left|\dfrac{5}{2}+x\right|=\dfrac{7}{3}\)
`=>`\(\left[{}\begin{matrix}\dfrac{5}{2}+x=\dfrac{7}{3}\\\dfrac{5}{2}+x=-\dfrac{7}{3}\end{matrix}\right.\)
\(\left[{}\begin{matrix}x=\dfrac{7}{3}-\dfrac{5}{2}=-\dfrac{1}{6}\\x=\left(-\dfrac{7}{3}\right)-\dfrac{5}{2}=-\dfrac{29}{6}\end{matrix}\right.\)
`=>`\(x=\left\{-\dfrac{1}{6};-\dfrac{29}{6}\right\}\)
