Rút gọn:

B= \(\left(2-\dfrac{a-3\sqrt{a}}{\sqrt{a}-3}\right)\left(2-\dfrac{5\sqrt{a}-\sqrt{ab}}{\sqrt{b}-5}\right)\)

Thực hiện phép tính:

a. \(2\sqrt{2}-3\sqrt{18}+4\sqrt{32}-2\sqrt{50}\)

b. \(\sqrt{6+2\sqrt{5}}+\sqrt{\left(\sqrt{5}-7\right)^2}\)

c. \(\dfrac{1}{2-\sqrt{6}}-\dfrac{1}{2+\sqrt{6}}\)

Rút gọn :

M= \(\left(\dfrac{2x+1}{x\sqrt{x}-1}-\dfrac{1}{\sqrt{x}-1}\right):\left(1-\dfrac{x+4}{x+\sqrt{x}+1}\right)\)

Rút gọn:

A= \(\left(\dfrac{\sqrt{a}}{9}-\dfrac{1}{\sqrt{a}}\right)^2\left(\dfrac{\sqrt{a}-3}{\sqrt{a}+3}-\dfrac{\sqrt{a}+3}{\sqrt{a}-3}\right)\)