Tính giá trị biểu thức
\[D=\sqrt[3]{70-\sqrt{4901}}+\sqrt[3]{70+\sqrt{4901}}\]
[tex]D=\sqrt[3]{70-\sqrt{4901}}+\sqrt[3]{70+\sqrt{4901}}\Rightarrow D^3=140+3\sqrt[3]{(70-\sqrt{4901})(70+\sqrt{4901})}(\sqrt[3]{70-\sqrt{4901}}+\sqrt[3]{70+\sqrt{4901}})\Rightarrow D^3=140-3D\Leftrightarrow D^3+3D-140=0[/tex]
[tex]\Leftrightarrow (D-5)(D^2+5D+28)=0\Rightarrow \begin{bmatrix} D=5 & & \\ D^2+5D+28=0 (VN_0) & & \end{bmatrix}[/tex]
Vậy $D=5$