$$\eqalign{
& y = \sqrt {{{x - \sqrt x } \over {2x - 5\sqrt x + 2}}} \cr
& DKXD: \cr
& \left\{ \matrix{
x \ge 0 \hfill \cr
{{x - \sqrt x } \over {2x - 5\sqrt x + 2}} \ge 0\,\,\left( 1 \right) \hfill \cr
2x - 5\sqrt x + 2 \ne 0\,\,\left( 2 \right) \hfill \cr} \right.\,\,\,\left( * \right) \cr
& Giai\,\,\left( 1 \right) \cr
& TH1:\,\,{{x - \sqrt x } \over {2x - 5\sqrt x + 2}} \ge 0 \cr
& \Leftrightarrow {{\sqrt x \left( {\sqrt x - 1} \right)} \over {\left( {\sqrt x - 2} \right)\left( {2\sqrt x - 1} \right)}} \ge 0 \cr
& \Leftrightarrow {{\sqrt x - 1} \over {\left( {\sqrt x - 2} \right)\left( {2\sqrt x - 1} \right)}} \ge 0 \cr
& TH1:\,\,\sqrt x - 1 \ge 0 \Leftrightarrow x \ge 1 \cr
& \Rightarrow \left( {\sqrt x - 2} \right)\left( {2\sqrt x - 1} \right) > 0 \cr
& \Leftrightarrow \left[ \matrix{
\sqrt x > 2 \hfill \cr
\sqrt x < {1 \over 2} \hfill \cr} \right. \Leftrightarrow \left[ \matrix{
x > 4 \hfill \cr
0 \le x < {1 \over 4} \hfill \cr} \right. \cr
& Ket\,\,hop\,\,Dk\,\,x \ge 1 \Rightarrow 1 \le x < 4 \cr
& TH2:\,\,\sqrt x - 1 \le 0 \Leftrightarrow 0 \le x < 1 \cr
& \Rightarrow \left( {\sqrt x - 2} \right)\left( {2\sqrt x - 1} \right) < 0 \cr
& \Leftrightarrow {1 \over 2} < \sqrt x < 2 \Leftrightarrow {1 \over 4} < x < 4 \cr
& Ket\,\,hop\,\,DK\,\,0 \le x < 1 \Rightarrow 0 \le x < 4 \cr
& Ket\,\,hop\,\,2TH \Rightarrow 0 \le x < 4 \cr
& Giai\,\,\left( 2 \right):\,\,2x - 5\sqrt x + 2 \ne 0 \Leftrightarrow \left\{ \matrix{
\sqrt x \ne 2 \hfill \cr
\sqrt x \ne {1 \over 2} \hfill \cr} \right. \Leftrightarrow \left\{ \matrix{
x \ne 4 \hfill \cr
x \ne {1 \over 4} \hfill \cr} \right. \cr
& He\,\,\left( * \right) \Leftrightarrow \left\{ \matrix{
x \ge 0 \hfill \cr
0 \le x < 4 \hfill \cr
x \ne 4;\,\,x \ne {1 \over 4} \hfill \cr} \right. \Leftrightarrow \left\{ \matrix{
0 \le x < 4 \hfill \cr
x \ne {1 \over 4} \hfill \cr} \right. \cr
& Vay\,\,D = \left[ {0;4} \right)\backslash \left\{ {{1 \over 4}} \right\} \cr} $$
