\(\sqrt{9-4\sqrt{5}}-\sqrt{14+6\sqrt{5}}=\sqrt{5-4\sqrt{5}+4}-\sqrt{9+6\sqrt{5}+5}\)
\(=\sqrt{\left(\sqrt{5}-2\right)^2}-\sqrt{\left(3+\sqrt{5}\right)^2}=\left(\sqrt{5}-2\right)-\left(3+\sqrt{5}\right)=-5\)
Trả lời:
\(\sqrt{9-4\sqrt{5}}-\sqrt{14+6\sqrt{5}}\)
\(=\sqrt{5-4\sqrt{5}+4}-\sqrt{9+6\sqrt{5}+5}\)
\(=\sqrt{\left(\sqrt{5}-2\right)^2}-\sqrt{\left(3+\sqrt{5}\right)^2}\)
\(=\sqrt{5}-2-3-\sqrt{5}\)
\(=-5\)