a, \(\frac{5}{9}+\left(\frac{3}{2}-2x\right)=-\frac{4}{7}\)
\(\Leftrightarrow\frac{3}{2}-2x=-\frac{4}{7}-\frac{5}{9}\)
\(\Leftrightarrow\frac{3}{2}-2x=\frac{-36}{63}-\frac{35}{63}\)
\(\Leftrightarrow\frac{3}{2}-2x=-\frac{71}{63}\)
\(\Leftrightarrow2x=\frac{3}{2}+\frac{71}{63}\)
\(\Leftrightarrow2x=\frac{189}{126}+\frac{142}{126}\)
\(\Leftrightarrow2x=\frac{331}{126}\)
\(\Leftrightarrow x=\frac{331}{126}:2\)
\(\Leftrightarrow x=\frac{331}{126}.\frac{1}{2}\)
\(\Leftrightarrow x=\frac{331}{252}\)
Vậy \(x=\frac{331}{252}\)
b, \(\frac{8}{13}-\left|x-\frac{1}{2}\right|=\frac{5}{7}\)
\(\Leftrightarrow\left|x-\frac{1}{2}\right|=\frac{8}{13}-\frac{5}{7}\)
\(\Leftrightarrow\left|x-\frac{1}{2}\right|=\frac{56}{91}-\frac{65}{91}\)
\(\Leftrightarrow\left|x-\frac{1}{2}\right|=-\frac{9}{91}\)( Vô lý )
Vậy không tìm được x thỏa mãn yêu cầu đầu bài