3 x *cos(3*x + 1)
d / 3 \ --\x *cos(3*x + 1)/ dx
Apply the product rule:
; to find :
Apply the power rule: goes to
; to find :
Let .
The derivative of cosine is negative sine:
Then, apply the chain rule. Multiply by :
Differentiate term by term:
The derivative of a constant times a function is the constant times the derivative of the function.
Apply the power rule: goes to
So, the result is:
The derivative of the constant is zero.
The result is:
The result of the chain rule is:
The result is:
Now simplify:
The answer is:
3 2 - 3*x *sin(3*x + 1) + 3*x *cos(3*x + 1)
/ 2 \ 3*x*\2*cos(1 + 3*x) - 6*x*sin(1 + 3*x) - 3*x *cos(1 + 3*x)/
/ 2 3 \ 3*\2*cos(1 + 3*x) - 27*x *cos(1 + 3*x) - 18*x*sin(1 + 3*x) + 9*x *sin(1 + 3*x)/