\[x^{3}\text{\ \ \ \ \ }\]
\[x = 4:\]
\[4^{3} = 4^{2} \cdot 4 = 16 \cdot 4 = 64.\]
\[x = - 5:\]
\[( - 5)^{3} = - 5^{3} = - 5^{2} \cdot 5 =\]
\[= - 25 \cdot 5 = - 125.\]
\[x = 0,4:\]
\[(0,4)^{3} = 0,064.\]
\[x = \frac{2}{3}:\]
\[\left( \frac{2}{3} \right)^{3} = \frac{2^{3}}{3^{3}} = \frac{8}{27}.\]