a: =>|x+1/5|=2
=>x+1/5=-2 hoặc x+1/5=2
=>x=9/5 hoặc x=-11/5
b: =>-5/4x-6/5x=-1/2-3/7
=>-49/24x=-7/14-6/14=-13/14
=>x=13/14:49/24=156/343
a, \(\left|x+\dfrac{1}{5}\right|-4=-2\)
\(\left|x+\dfrac{1}{5}\right|=\left(-2\right)+4\)
\(\left|x+\dfrac{1}{5}\right|=2\)\(\left\{{}\begin{matrix}x+\dfrac{1}{5}=2\\x+\dfrac{1}{5}=-2\end{matrix}\right.\)
với \(x+\dfrac{1}{5}=2\Rightarrow x=2-\dfrac{1}{5}\)\(\) hay \(x=\dfrac{9}{5}\)
với \(x+\dfrac{1}{5}=-2\Rightarrow x=-2-\dfrac{1}{5}\) hay \(x=-\dfrac{11}{5}\)
b, \(-\dfrac{15}{12}x+\dfrac{3}{7}=\dfrac{6}{5}x-\dfrac{1}{2}\)
\(\dfrac{6}{5}x+\dfrac{5}{4}x=\dfrac{3}{7}+\dfrac{1}{2}\)
\(\left(\dfrac{6}{5}+\dfrac{5}{4}\right)x=\dfrac{6}{14}+\dfrac{7}{14}=\dfrac{13}{14}\)
\(\dfrac{49}{20}x=\dfrac{13}{14}\)
\(x=\dfrac{13}{14}:\dfrac{49}{20}\)
\(x=\dfrac{13}{14}.\dfrac{20}{49}=\dfrac{260}{686}\)
\(x=\dfrac{130}{343}\)
