Rút gọn biểu thức sau A= (1- 2 căn x/ 3 căn x+1- (1-2 căn x)/(3 căn x+1):(6 căn x+5/ (3 căn x+1)

* Hướng dẫn giải

$\begin{array}{l}\text{A=}\left(1-\frac{2\sqrt{x}}{3\sqrt{x}+1}-\frac{1-2\sqrt{x}}{1-9x}\right):\left(\frac{6\sqrt{x}+5}{3\sqrt{x}+1}-2\right)\\ =\frac{9x-1-2\sqrt{x}(3\sqrt{x}-1)+1-2\sqrt{x}}{\left(3\sqrt{x}+1\right)\left(3\sqrt{x}-1\right)}:\frac{6\sqrt{x}+5-2(3\sqrt{x}+1)}{3\sqrt{x}+1}\\ =\frac{9x-2\sqrt{x}-6x+2\sqrt{x}}{\left(3\sqrt{x}+1\right)\left(3\sqrt{x}-1\right)}.\frac{3\sqrt{x}+1}{6\sqrt{x}+5-6\sqrt{x}-2}\\ =\frac{3x}{3\sqrt{x}-1}.\frac{1}{3}=\frac{x}{3\sqrt{x}-1}\end{array}$