The derivative of a constant times a function, c⋅f(x)c \cdot f(x)c⋅f(x), is:
0
c⋅f′(x)c \cdot f'(x)c⋅f′(x)
f′(x)f'(x)f′(x)
c+f′(x)c + f'(x)c+f′(x)