Rút gọn biểu thức: A = $\sqrt{29-12\sqrt{5}}-2\sqrt[3]{16+8\sqrt{5}}.$

Bùi Ngọc Diễm

$A=\sqrt{29-12\sqrt{5}}-2\sqrt[3]{16+8\sqrt{5}}$

$A=\sqrt{\left(2\sqrt{5}\right)^2+2.2\sqrt{5}.3+3^2}-2\sqrt[3]{1+3.1^2.\sqrt{5}+3.\sqrt{5^2}+\left(\sqrt{5}\right)^3}$

$A=\sqrt{\left(2\sqrt{5}-3\right)^2}-2\sqrt[3]{\left(1+\sqrt{5}\right)^3}$

$A=2\sqrt{5}-3-2\left(1+\sqrt{5}\right)=-5$

KL...