Lời giải:
Đặt $\frac{1}{x+1}=a; \frac{1}{y-1}=b$ thì hpt trở thành:
\(\left\{\begin{matrix}
3a-4b=1\\
5a+6b=8\end{matrix}\right.\Leftrightarrow \left\{\begin{matrix}
15a-20b=5\\
15a+18b=24\end{matrix}\right.\)
\(\Rightarrow (15a+18b)-(15a-20b)=24-5\)
$\Leftrightarrow 38b=19$
$\Leftrightarrow b=\frac{1}{2}$
$\Rightarrow a=\frac{1}{3}(4b+1)=1$
Vậy $(a,b)=(\frac{1}{x+1}, \frac{1}{y-1})=(1, \frac{1}{2})$
$\Leftrightarrow (x,y)=(0,3)$