Question

Tính:

\(\sqrt{\dfrac{9}{7-4\sqrt{3}}}-\sqrt{\dfrac{4}{7+4\sqrt{3}}}\)

Answer 1

\(=\dfrac{\sqrt{9}}{\sqrt{7-2.2.\sqrt{3}}}-\dfrac{\sqrt{4}}{\sqrt{7+2.2.\sqrt{3}}}\\ =\dfrac{3}{\sqrt{\left(2-\sqrt{3}\right)^2}}-\dfrac{2}{\sqrt{\left(2+\sqrt{3}\right)^2}}\\ =\dfrac{3}{2-\sqrt{3}}-\dfrac{2}{2+\sqrt{3}}\\ =\dfrac{3\left(2+\sqrt{3}\right)-2\left(2-\sqrt{3}\right)}{4-3}\\ =6+3\sqrt{3}-4+2\sqrt{3}\\ =2+5\sqrt{3}\)

Answer 2

giúp mk vs cần gấp lắm ạ!!!!!