2*cos(x) -------- 3
d /2*cos(x)\ --|--------| dx\ 3 /
The derivative of a constant times a function is the constant times the derivative of the function.
The derivative of cosine is negative sine:
So, the result is:
The answer is:
-2*sin(x) --------- 3
-2*cos(x) --------- 3
2*sin(x) -------- 3