Question 354693
{{{x^(2/3)-2x^(1/3)-8=0}}}
{{{(x^(1/3) - 4)(x^(1/3) + 2) = 0}}}
so either {{{(x^(1/3) - 4) = 0}}} or {{{(x^(1/3) + 2)=0}}}
Solve for that
{{{(x^(1/3) - 4) = 0}}}
{{{x^(1/3) = 4}}}
{{{x = 4^3 = 64}}} 
or
{{{(x^(1/3) + 2)=0}}}
{{{x^(1/3) = -2}}}
{{{x = -8}}}