Apply the product rule:
; to find :
Differentiate term by term:
Apply the power rule: goes to
The derivative of the constant is zero.
The result is:
; to find :
The derivative of sine is cosine:
The result is:
Now simplify:
The answer is:
(x - 8)*cos(x) + sin(x)
2*cos(x) - (-8 + x)*sin(x)
-(3*sin(x) + (-8 + x)*cos(x))