Question

* Thực hiện phép tính.

a.\(2\sqrt{18}-9\sqrt{50}+3\sqrt{8}\)

b.\(\left(\sqrt{7}-\sqrt{3}\right)^2+7\sqrt{84}\)

c.\(\left(\dfrac{6-2\sqrt{2}}{3-\sqrt{2}}-\dfrac{5}{\sqrt{5}}\right).\dfrac{1}{2-\sqrt{5}}\)

d.\(\sqrt{\left(2-\sqrt{5}\right)^2-\sqrt{5}}\)

Answer 1

a) \(\text{2}\sqrt{\text{18}}-9\sqrt{50}+3\sqrt{8}\)

= \(\text{6}\sqrt{\text{2}}-45\sqrt{2}+6\sqrt{2}\)

= \(-33\sqrt{2}\)

Answer 2

b) = \(7-2.\sqrt{7}.\sqrt{3}+3+7.2\sqrt{21}\)

= \(10-2\sqrt{21}+14\sqrt{21}\)

= \(10+12\sqrt{21}\)