Giải hệ phương trình :
a,\(\left\{{}\begin{matrix}\dfrac{3}{x+1}+\dfrac{1}{y-1}=2\\\dfrac{2}{x+1}-\dfrac{3}{y-1}=5\end{matrix}\right.\)
b,\(\left\{{}\begin{matrix}\dfrac{1}{x+1}-\dfrac{3}{y-1}=1\\\dfrac{2}{x+1}+\dfrac{4}{y-1}=3\end{matrix}\right.\)