\(xy-y\sqrt{x}+\sqrt{x}-1\)
\(=y\left(x-\sqrt{x}\right)+\left(\sqrt{x}-1\right)\)
\(=y\sqrt{x}\left(\sqrt{x}-1\right)+\left(\sqrt{x}-1\right)\)
\(\left(\sqrt{x}-1\right)\left(y\sqrt{x}+1\right)\)
\(xy-y\sqrt{x}+\sqrt{x}-1\)
\(=\left(\sqrt{x}\right)^2.y-y\sqrt{x}+\sqrt{x}-1\)
\(=y\sqrt{x}\left(\sqrt{x}-1\right)+\sqrt{x}-1\)
\(=\left(\sqrt{x}-1\right)\left(y\sqrt{x}+1\right)\)
\(xy-y\sqrt{x}+\sqrt{x}-1=\left(xy-y\sqrt{x}\right)+\left(\sqrt{x}-1\right)\)
\(=y\sqrt{x}.\left(\sqrt{x}-1\right)+\left(\sqrt{x}-1\right)=\left(\sqrt{x}-1\right)\left(y\sqrt{x}+1\right)\)