$\left\{{{3\sqrt{x-1}+2\sqrt{y}=13}\atop{2\sqrt{x-1}-\sqrt{y}=4}}\right.$
$\text{(ĐK: x≥1; y≥0)}$
$\text{Đặt: }\sqrt{x-1}=a; \sqrt{y}=b \text{(ĐK: a≥0; b≥0)}$
$\Rightarrow \left\{{{3a+2b=13}\atop{2a-b=4}}\right.$
$\Leftrightarrow \left\{{{6a+4b=26}\atop{6a-3b=12}}\right.$
$\Leftrightarrow \left\{{{7b=14}\atop{6a-3b=12}}\right.$
$\Leftrightarrow \left\{{{b=2}\atop{6a-3.2=12}}\right.$
$\Leftrightarrow \left\{{{a=3}\atop{b=2}}\right.\text{ (thỏa mãn)}$
$\Rightarrow \left\{{{\sqrt{x-1}=3}\atop{\sqrt{y}=2}}\right.$
$\Leftrightarrow \left\{{{x=10}\atop{y=4}}\right.\text{ (thỏa mãn)}$
$\Rightarrow\text{(x; y)=(10; 4)}$
