Question

If f(x)=sin^3 (4x), find f'(pi/3).

Answer 1

take f'(x).
\[f'(x) = 3(\sin(4x))^2(4)\]
\[f'(x) = 12(\sin(4x))^2)\]
plug in \[\frac{ \pi }{ 3 }\] and you have the answer.

Answer 2

A. -3/2, B. -9/2, C. -3sqrt(3), D. 3sqrt(3), E. -9/8. Which is the answer? When I plug in the value that you said, none of them are correct.

Answer 3

shoot. i did f'(x) wrong. sorry.
\[f'(x) = 3(\sin(4x))^2(\cos(4x))(4)\]
simplify.
then plug in.

Answer 4

the answer is one of the choices. i'll let you figure it out,

Answer 5

hint when you plug in \[\frac{ \pi }{ 3}\] to sin(4x).....what is \[\sin(\frac{ 4\pi }{ 3 })\]

Answer 6

Thanks, guys.