Volume of cube = [tex] (Side)^3 [/tex]
=> 30 = [tex](Side)^3[/tex]
So, Side = [tex] \sqrt[3]{30} [/tex]
Side = 3.107232......... and goes on.
Cube root of 30 is not a natural number or a terminating decimal number.
It is a non-terminating decimal number. So, physically it is not possible to find an edge length that will give volume 30 cubic units