x-2m \sqrt{x-1} +m -4 = 0
$ĐK: x-1\geq 0$
$ĐK: x-1\geq 0 x-2m\sqrt{x-1} +m -4=0 \Leftrightarrow m(1-2\sqrt{x-1})=4-x (1) Xét 1-2\sqrt{x-1} =0 \Leftrightarrow 2\sqrt{x-1}=1 \Leftrightarrow \sqrt{x-1} = \frac{1}{2} \Leftrightarrow x-1 = \frac{1}{4} (Vì x-1>0) \Leftrightarrow x = \frac{5}{4} (TM) Thay x=\frac{5}{4} vào (1), ta có: (1) \Leftrightarrow 0m=4-\frac{5}{4} (Vô lí) Nếu 1-2\sqrt{x-1} \neq 0 \Leftrightarrow x\neq \frac{5}{4} \Rightarrow (1) \Leftrightarrow m(1-2\sqrt{x-1})=4-x \Leftrightarrow m=\frac{4-x}{1-2\sqrt{x-1}}$