Question

I have a question about Calculus. This problem doesn't seem hard but I'm missing something.
s=t^7cost-7tsint-7cost
I need to take the derivative

Answer 1

respect to t?

Answer 2

= \[7t^6 \cos t- t^7\sin t -7\sin t + 7t \cos t +7 \sin t = \]\[7t^6 \cos t- t^7\sin t + 7t \cos t]