Question

let f(x)=2x^4 - 4x^2 find all c in the interval (-3, 3) such that f'(c) = 0. PLEASE HELP AND SHOW ALL STEPS!

Answer 1

f'(x) = 2x^2 - 8x = 0
8x = 2x^2
4 = 2x
2 = x

Answer 2

There are a couple of errors in what Diarmuid has written, beginning with the derivative.

Can you calculate the derivative yourself?

Answer 3

Damn. sorry. I should have read the question more carefully
f'(x) = 8x^3 -8x
I was wondering about the wording when it looked like there was only one minimum.

0 = 8x^3 -8x
1 = x^2
x = + - 1 and of course 0 (should there be a mathematical way of getting the zero?)
so points are (-1,0), (0,0), 1,0)