Question

Thực hiện phép tính:
a)2\(\sqrt{50}\) -3 \(\sqrt{32}\) - \(\sqrt{162}\) + 5\(\sqrt{98}\)
b)\(\sqrt{8+2\sqrt{7}}+\sqrt{11-4\sqrt{7}}\)
c)\(\dfrac{10}{\sqrt{5}}+\dfrac{8}{3+\sqrt{5}}-\dfrac{\sqrt{18}-3\sqrt{5}}{\sqrt{2}-\sqrt{5}}\)
-GIÚP MÌNH VỚI Ạ-

Answer 1

a) \(2\sqrt{50}-3\sqrt{32}-\sqrt{162}+5\sqrt{98}\)

=\(2.5\sqrt{2}-3.4\sqrt{2}-9\sqrt{2}+5.7\sqrt{2}\)

= \(10\sqrt{2}-12\sqrt{2}-9\sqrt{2}+35\sqrt{2}\)

= \(24\sqrt{2}\)

b) \(\sqrt{8+2\sqrt{7}}+\sqrt{11-4\sqrt{7}}\)

= \(\sqrt{7+2\sqrt{7}+1}+\sqrt{7-4\sqrt{7}+4}\)

= \(\sqrt{\left(\sqrt{7}+1\right)^2}+\sqrt{\left(\sqrt{7}-2\right)^2}\)

= \(\sqrt{7}+1+\sqrt{7}-2\)

= \(2\sqrt{7}-1\)

c) \(\dfrac{10}{\sqrt{5}}+\dfrac{8}{3+\sqrt{5}}-\dfrac{\sqrt{18}-3\sqrt{5}}{\sqrt{2}-\sqrt{5}}\)

= \(2\sqrt{5}+6-2\sqrt{5}-3\)

= 3