Giải thích các bước giải:
a) $\sqrt[]{27+8\sqrt[]{11}}$
= $\sqrt[]{16+2.4.\sqrt[]{11}+11}$
= $\sqrt[]{4^2+2.4.\sqrt[]{11}+(\sqrt[]{11})^2}$
= =$\sqrt[]{(4+\sqrt[]{11})^2}$
= $4+\sqrt[]{11}$
b) $\sqrt[]{37-20\sqrt[]{3}}$
= $\sqrt[]{25-2.5.2\sqrt[]{3}+12}$
= $\sqrt[]{5^2-2.5.2\sqrt[]{3}+(2\sqrt[]{3})^2}$
= $\sqrt[]{(5-2\sqrt[]{3})^2}$
= $5 - 2\sqrt[]{3}$