Answer:
[tex]\large\boxed{1.\ 3}\\\boxed{2.\ 81}[/tex]
Step-by-step explanation:
[tex]\sqrt[3]{a}=b\iff b^3=a\\\\\sqrt{a}=b\iff b^2=a\ for\ a,b\geq0\\==========================\\\\1.\ \sqrt[n]{8}=2\iff2^n=8\Rightarrow2^n=2^3\Rightarrow \boxed{n=3}\\\\2.\ \sqrt[4]{n}=3\iff 3^4=n\Rightarrow \boxed{n=81}[/tex]
