The equation for the volume of a cube is [tex]V = s^{3} [/tex], where V = volume and s = length of each side of the cube.
You are told that the volume, V = [tex]\frac{1}{8}\: ft^{3} [/tex]. Plug that value into the volume equation and solve for s, the length of each side:
[tex]V = s^{3}\\
\frac{1}{8} = s^{3}\\
s = \sqrt[3]{\frac{1}{8}} \\
s = \frac{1}{2} [/tex]
The length of each edge of the cube is [tex]\frac{1}{2} \:ft[/tex].