Solución
f
′
(
x
)
=
4
x
4
+
2
x
2
−
2
x
x
4
f'\left( x \right) = {{4{x^4} + 2{x^2} - 2x} \over {{x^4}}}
f
′
(
x
)
=
x
4
4
x
4
+
2
x
2
−
2
x