Giải thích các bước giải:
$B=(\dfrac{2+\sqrt{x}}{\sqrt{x}}-\dfrac{\sqrt{x}}{-2+\sqrt{x}}):\dfrac{4\sqrt{x}-4}{x-2\sqrt{x}}$
$\to B=(\dfrac{(2+\sqrt{x})(\sqrt{x}-2)}{\sqrt{x}(\sqrt{x}-2)}-\dfrac{\sqrt{x}.\sqrt{x}}{\sqrt{x}(\sqrt{x}-2)}):\dfrac{4(\sqrt{x}-1)}{\sqrt{x}(\sqrt{x}-2)}$
$\to B=\dfrac{(2+\sqrt{x})(\sqrt{x}-2)-\sqrt{x}.\sqrt{x}}{\sqrt{x}(\sqrt{x}-2)}:\dfrac{4(\sqrt{x}-1)}{\sqrt{x}(\sqrt{x}-2)}$
$\to B=\dfrac{x-4-x}{\sqrt{x}(\sqrt{x}-2)}.\dfrac{\sqrt{x}(\sqrt{x}-2)}{4(\sqrt{x}-1)}$
$\to B=\dfrac{-4}{\sqrt{x}(\sqrt{x}-2)}.\dfrac{\sqrt{x}(\sqrt{x}-2)}{4(\sqrt{x}-1)}$
$\to B=\dfrac{-1}{\sqrt{x}-1}$
