Question

Given f (x) = cos^2 (x) what is the correct expansion for the first derivative of f (x)
from first principals:

Answer 1

i think it is -sin2x

Answer 2

perfect condition for me now, hihi..

Answer 3

its wrong

Answer 4

it is -2cosxsinx

Answer 5

use the chain rule

Answer 6

\[\cos ^{2}x = (\cos x)^{2}\]
\[f \prime (x) = 2 \cos x \times -\sin x\]

Answer 7

u need 2 use the first principal