In order to find the simplest radical form, we first need to factorate the number inside the square root. So we have that:
[tex]108=2\cdot2\cdot3\cdot3\cdot3[/tex]Then we will need to use the following property:
[tex]\sqrt[c]{a^b}=a^{}\sqrt[c]{a^{b-c}},\text{ b>c}[/tex]So we have that:
[tex]\sqrt[]{108}=\sqrt[]{2\cdot2\cdot3\cdot3\cdot3}=\sqrt[]{2^2\cdot3^3}=2\cdot3\sqrt[]{2^03^1}=6\sqrt[]{3}[/tex]So the simplest radical form of √108 is 6√3.