Cho E = 4x / căn x-3 . Tìm x để căn A+3 ( 3 nằm trong căn A ) - căn A =1

\[\begin{array}{l} A = \frac{{4x}}{{\sqrt x - 3}}\,\,\,\,\\ DK:\,\,\,x \ge 0;\,\,\,x \ne 9.\\ \sqrt {A + 3} - \sqrt A = 1\,\,\,\,\,\,\,\,\left( {A \ge 0} \right)\\ \Leftrightarrow \sqrt {A + 3} = 1 + \sqrt A \\ \Leftrightarrow A + 3 = 1 + A + 2\sqrt A \\ \Leftrightarrow 2\sqrt A = 2\\ \Leftrightarrow \sqrt A = 1\\ \Leftrightarrow A = 1\\ \Leftrightarrow \frac{{4x}}{{\sqrt x - 3}}\, = 1\\ \Leftrightarrow 4x = \sqrt x - 3\\ \Leftrightarrow 4x - \sqrt x + 3 = 0\\ \Leftrightarrow pt\,\,\,VN.\\ Vay\,\,k\,\,\,co\,\,\,x\,\,\,thoa\,\,man. \end{array}\]