Question

Derivar U(z) = 3/x^3 + x^3/3

Answer 1

$U\left(x\right)=\dfrac{3}{x^{3}}+\dfrac{x^{3}}{3}\\ \\ \\ \dfrac{\mathrm{d}U}{\mathrm{d}x}=\dfrac{\mathrm{d}}{\mathrm{d}x}\left(\dfrac{3}{x^{3}}+\dfrac{x^{3}}{3} \right )\\ \\ \\ \dfrac{\mathrm{d}U}{\mathrm{d}x}=\dfrac{\mathrm{d}}{\mathrm{d}x}\left(3x^{-3}+\dfrac{x^{3}}{3} \right )\\ \\ \\ \dfrac{\mathrm{d}U}{\mathrm{d}x}=-3\cdot 3x^{-3-1}+\dfrac{3x^{3-1}}{3}\\ \\ \\ \dfrac{\mathrm{d}U}{\mathrm{d}x}=-9x^{-4}+\dfrac{3x^{2}}{3}\\ \\ \\ \boxed{\dfrac{\mathrm{d}U}{\mathrm{d}x}=-\dfrac{9}{x^{4}}+x^{2}}$