Practice problem
Mark all functions fff below such that (f⋅g)′=f⋅g′(f\cdot g)' = f\cdot g'(f⋅g)′=f⋅g′ for all differentiable functions ggg.
f(x)=xf(x) = xf(x)=x
f(x)=π2+πf(x) = \pi^2 + \pif(x)=π2+π
f(x)=0f(x) = 0f(x)=0
f(x)=sinxf(x) = \sin{x}f(x)=sinx
Any function f(x)f(x)f(x) whose derivative function, f′(x)f'(x)f′(x), is zero.
Type a concept, like “slope” or “photosynthesis”.