\(\sqrt[3]{20-14\sqrt{2}}.\sqrt[3]{20+14\sqrt{2}}\) = ?
\(2\). \(8\). \(4\). \(6\). Hướng dẫn giải:\(\sqrt[3]{20-14\sqrt{2}}.\sqrt[3]{20+14\sqrt{2}}=\sqrt[3]{\left(20-14\sqrt{2}\right)\left(20+14\sqrt{2}\right)}=\)\(\sqrt[3]{20^2-\left(14\sqrt{2}\right)^2}=\sqrt[3]{8}=2\).
