\(A=\dfrac{y-5\sqrt{y}}{\sqrt{y}-5}+\dfrac{10+2\sqrt{x}-5\sqrt{y}-\sqrt{xy}}{5+\sqrt{x}}\)
\(=\dfrac{\sqrt{y}\left(\sqrt{y}-5\right)}{\sqrt{y}-5}+\dfrac{\left(2\sqrt{x}+10\right)-\left(\sqrt{xy}+5\sqrt{y}\right)}{\sqrt{x}+5}\)
\(=\sqrt{y}+\dfrac{2\left(\sqrt{x}+5\right)-\sqrt{y}\left(\sqrt{x}+5\right)}{\sqrt{x}+5}\)
\(=\sqrt{y}+2-\sqrt{y}=2\)
A+x<5
=>2+x<5
=>x<3
mà x>=0 và x nguyên
nên \(x\in\left\{0;1;2\right\}\)
=>Nghiệm nguyên lớn nhất là x=2