recall that a cube has all equal sides, check the picture below.
[tex]\bf \textit{volume of a cube}\\\\
V=x^3~~
\begin{cases}
x=side's~length\\[-0.5em]
\hrulefill\\
V=5.12
\end{cases}\implies 5.12=x^3
\\\\\\
\sqrt[3]{5.12}=x\implies 1.72354775\approx x[/tex]
