Question

rút gọn B

Answer 1

\(đkx\ne9;x>0\\ B=\dfrac{\sqrt{x}\left(\sqrt{x}-3\right)-\left(\sqrt{x}+1\right)\left(\sqrt{x}+3\right)+x+\sqrt{x}+12}{x-9}\\ =\dfrac{x-3\sqrt{x}-\left(x+\sqrt{x}+3\sqrt{x}+3\right)+x+\sqrt{x}+12}{x-9}\\ =\dfrac{2x-2\sqrt{x}+12-x-4\sqrt{x}-3}{x-9}\\ =\dfrac{x-6\sqrt{x}+9}{x-9}=\dfrac{\left(\sqrt{x}-3\right)^2}{x-9}=\dfrac{\sqrt{x}-3}{\sqrt{x}+3}\)