Câu hỏi:   

A A= \sqrt{2};B=\frac{-3\sqrt{x}}{x-4}

B A= -\sqrt{2};B=\frac{-3\sqrt{x}}{x-4}

C A= -\sqrt{2};B=\frac{\sqrt{x}}{x-4}

D A= \sqrt{2};B=\frac{\sqrt{x}}{x-4}