Aloha :)
$$y'(x)=\left(x^{2/3}-\frac{1}{x^{2/3}}\right)'=\left(x^{2/3}-x^{-2/3}\right)'=\frac{2}{3}x^{2/3-1}-\left(-\frac{2}{3}\right)x^{-2/3-1}$$$$\phantom{y'(x)}=\frac{2}{3}x^{-1/3}+\frac{2}{3}x^{-5/3}=\frac{2}{3}\left(\frac{1}{x^{1/3}}+\frac{1}{x^{5/3}}\right)=\frac{2}{3}\left(\frac{1}{\sqrt[3]x}+\frac{1}{x\sqrt[3]{x^2}}\right)$$
$$f'(x)=\left(4x^{2\pi}\right)'=4\cdot2\pi x^{2\pi-1}=8\pi x^{2\pi-1}$$