\(1,A=\left(\dfrac{y\sqrt{y}-1}{y-\sqrt{y}}-\dfrac{y\sqrt{y}+1}{y+\sqrt{y}}\right):\dfrac{2\left(y-2\sqrt{y}+1\right)}{y-1}\left(y>0;y\ne1\right)\\ A=\left[\dfrac{\left(\sqrt{y}-1\right)\left(y+\sqrt{y}+1\right)}{\sqrt{y}\left(\sqrt{y}-1\right)}-\dfrac{\left(\sqrt{y}+1\right)\left(y-\sqrt{y}+1\right)}{\sqrt{y}\left(\sqrt{y}+1\right)}\right]:\dfrac{2\left(\sqrt{y}-1\right)^2}{\sqrt{y}-1}\\ A=\dfrac{y+\sqrt{y}+1-\left(y-\sqrt{y}+1\right)}{\sqrt{y}}\cdot\dfrac{1}{2\left(\sqrt{y}-1\right)}\\ A=2\cdot\dfrac{1}{2\left(\sqrt{y}-1\right)}=\dfrac{1}{\sqrt{y}-1}\)
\(b,B\in Z\Leftrightarrow\dfrac{1}{\sqrt{y}-1}\in Z\Leftrightarrow1⋮\sqrt{y}-1\\ \Leftrightarrow\sqrt{y}-1\inƯ\left(1\right)=\left\{-1;1\right\}\\ \Leftrightarrow\sqrt{y}\in\left\{0;2\right\}\\ \Leftrightarrow y\in\left\{0;4\right\}\)
