Question

Rút gọn biểu thức:

a) \(-7\sqrt{\dfrac{1}{7}}\);

b) \(6\sqrt{\dfrac{11}{6}}-\sqrt{66}\).

Answer 1

a. \( - 7\sqrt {\frac{1}{7}}  = -\sqrt {{{\left( { - 7} \right)}^2}.\frac{1}{7}}  = -\sqrt {49.\frac{1}{7}}  = -\sqrt 7 .\)

b. \(6\sqrt {\frac{{11}}{6}}  - \sqrt {66}  = \sqrt {{6^2}.\frac{{11}}{6}}  - \sqrt {66}  = \sqrt {6.11}  - \sqrt {66}  = \sqrt {66}  - \sqrt {66}  = 0.\)