Solution:
Given the expression below
[tex]\sqrt{108}[/tex]
To find the equivalence of the given expression, we will multiply the radicals to find the odd one out
[tex]\begin{gathered} \sqrt{2}\times\sqrt{54}=\sqrt{108} \\ \sqrt{3}\times\sqrt{36}=\sqrt{108} \\ \sqrt{5}\times\sqrt{2}=\sqrt{105} \\ \sqrt{6}\times\sqrt{18}=\sqrt{108} \end{gathered}[/tex]
From the deductions above,
Hence, the radical expression that is not equivalent to the given expression is
[tex]\sqrt{5}\times\sqrt{21}[/tex]
The answer is option C
