Question

y=cos^7(sin3x)

I think i figured out the right answer:
-21cos^6x(sin3x)sin(sin3x)cos(3x)

I'm just trying to input it into my online homework and it keeps saying its incorrect, what am i doing wrong!?!?!

Answer 1

What exactly are you trying to do with this equation?

Answer 2

\[y=\cos^7(\sin3x)\]\[y=[\cos~(\sin3x)]^7\]taking the derivative, because that is what you seem to try to do.
\[y' =7[\cos~(\sin3x)]^6\times (-\sin~(\sin3x)~)\times (~\cos(3x)~)\times 3\]\[y' =-63[\cos^6(\sin3x)](\sin~(\sin3x)~)\times (~\cos(3x)~)\]you forgot the chain rule for 3x.

Answer 3

there is a chain rule 3 times. and I hope you figure out what you left out....

Answer 4

thanks!