Question

Let f(x) = 2 x^4 - 16 x^2 + 4.

Use the first derivative test to find the value(s) of x for which f(x) has a relative maximum and list them in increasing order.

I know i'm on the right track
f(x)= 8x^3-32x=0
8x(x^2-4)=0
x=0,x=02,x=-2 then what??

Answer 1

so find the min and the max

Answer 2

then check the derivatives sign(+/-) before and ater the values u found..

Answer 3

x=0,x=2,x=-2

Answer 4

nt like that .... if -inf<x<0 f'(x)<0... like that..

Answer 5

so plug in for x?