What is the derivative of x^(2/3)?

Be $y = {a}^{n}$, then $\frac{\mathrm{dy}}{\mathrm{dx}} = n \cdot {a}^{n - 1}$
$\frac{\mathrm{dy}}{\mathrm{dx}} = {x}^{\frac{3}{2} - 1} = {x}^{\frac{1}{2}} = \sqrt{x}$