\(A=\dfrac{1+2\sqrt{x}+x-4\sqrt{x}}{1-\sqrt{x}}=\dfrac{1-2\sqrt{x}+x}{1-\sqrt{x}}=\dfrac{\left(1-\sqrt{x}\right)^2}{1-\sqrt{x}}=1-\sqrt{x}\)Câu trả lời: \(A=\dfrac{1+2\sqrt{x}+x-4\sqrt{x}}{1-\sqrt{x}}=\dfrac{1-2\sqrt{x}+x}{1-\sqrt{x}}=\dfrac{\left(1-\sqrt{x}\right)^2}{1-\sqrt{x}}=1-\sqrt{x}\)