We will have the following:
[tex]\begin{gathered} 3\sqrt[4]{2}=\sqrt[4]{3^4\ast2}=\sqrt[4]{81\ast2} \\ \\ =\sqrt[4]{162} \end{gathered}[/tex]***Explanation**
If want to "enter" a value that multiplies a root, then we will have to follow:
[tex]a\sqrt[b]{c}=\sqrt[b]{a^bc}[/tex]