\(7,=\sqrt{2}-3\left(B\right)\\ 11,=\dfrac{\sqrt{12x^3y}}{4y}=\dfrac{2x\sqrt{3xy}}{4y}=\dfrac{x}{2y}\sqrt{3xy}\left(C\right)\)
\(\sqrt{\dfrac{3x^3}{4y}}=\sqrt{\left(\dfrac{x}{2y}\right)^2.3xy}=\dfrac{x}{2y}\sqrt{3xy}\)
\(\sqrt[3]{\left(\sqrt{2}-3\right)^3}=\sqrt{2}-3\) (khi lấy căn bậc 3 thì ko lấy trị tuyệt đối)