Giá trị biểu thức $\left( {\sqrt 5  + \sqrt 2 } \right)\sqrt {7 - 2\sqrt {10} }$ là

$\sqrt {\dfrac{A}{{BC}}}  = \dfrac{{\sqrt {ABC} }}{B}$

$\sqrt {\dfrac{A}{B}}  =  - \dfrac{{\sqrt {ABC} }}{{BC}}$           

$\sqrt {\dfrac{A}{{BC}}}  = \dfrac{{\sqrt {ABC} }}{{BC}}$

$\sqrt {\dfrac{A}{{BC}}}  = \dfrac{{ABC}}{{\sqrt {BC} }}$

$3 + 4\sqrt 2$

$4$

$2$

$4\sqrt 2$

$9\left( {2 - y} \right)$

$81{\left( {2 - y} \right)^2}$

$9{\left( {2 - y} \right)^2}$

$- 9{\left( {2 - y} \right)^2}$

$\sqrt {5{y^2}}$

$\sqrt {25{y^3}}$

$\sqrt {5{y^3}}$

$\sqrt {25y\sqrt y }$

$16\sqrt 2  + 12\sqrt 3$

$15\sqrt 3$

$12\sqrt 3$

$16\sqrt 2$

$\dfrac{{\sqrt 6 }}{6}$

$\sqrt 6$

$\dfrac{{\sqrt 6 }}{2}$

$\dfrac{{\sqrt 6 }}{3}$

$B > 1$

$B < 1$

$B = 1$

$B \le 1$