Answer
$\displaystyle \frac{4(1+2x)}{x^{2/3}}$
Work Step by Step
$4x^{-2/3}+8x^{1/3}=4x^{-2/3}+4\cdot 2\cdot x^{-\frac{2}{3}+1}$
$=4x^{-2/3}+4\cdot 2\cdot x^{-2/3}\cdot x \qquad$... factor out $4x^{-\frac{2}{3}}$
$=4x^{-2/3}(1+2x)\qquad $... $a^{-n}=\displaystyle \frac{1}{a^{n}}$
$=\displaystyle \frac{4(1+2x)}{x^{2/3}}$
