Question

Let
f
(
x
)
=
x
4
−
2
x
2
f(x)=x4−2x2
. Find the all
c
c
(where
c
c
is the interception on the x-axis ) in the interval (-2, 2) such that
f
′
(
x
)
=
0
f′(x)=0
. ( Hint use Rolle's theorem )