2.4 Lösning 3d

\[ y = 7\,x^4 - {25 \over x} = 7\,x^4 - 25\cdot{1 \over x} \]

\[ y\,' = 28\,x^3 - 25\cdot\left(-{1 \over x^2}\right) = 28\,x^3 + {25 \over x^2} \]