[tex]\bf 27x^3=8\implies x^3=\cfrac{8}{27}\implies x = \sqrt[3]{\cfrac{8}{27}}\implies x = \sqrt[3]{\cfrac{2^3}{3^3}} \\\\\\ x = \cfrac{\sqrt[3]{2^3}}{\sqrt[3]{3^3}}\implies x=\cfrac{2}{3}[/tex]