[tex]\sqrt[3]{z} = 1\\\\z^{\frac{1}{3} } =1\\\\z^{\frac{1}{3} } =1^{x} \\\\\frac{1}{3} = x\\[/tex]

logo temos que

[tex]z^{\frac{1}{3} } =1^{x} \\\\z^{\frac{1}{3} } = 1^{\frac{1}{3} } \\[/tex]

Que ficará...

[tex]\sqrt[3]{1} = 1[/tex]