[tex]\bf \begin{cases}
400=2\cdot 2\cdot 2\cdot 2\cdot 5\cdot 5\\
\qquad 2^4\cdot 5\cdot 5
\end{cases}\qquad \cfrac{\sqrt[4]{400}}{\sqrt[4]{5}}\implies \cfrac{\sqrt[4]{2^4\cdot 5\cdot 5}}{\sqrt[4]{5}}
\\\\\\
\cfrac{2\sqrt[4]{5\cdot 5}}{\sqrt[4]{5}}\implies \cfrac{2\sqrt[4]{5}\cdot \underline{\sqrt[4]{5}}}{\underline{\sqrt[4]{5}}}\implies 2\sqrt[4]{5}[/tex]
