Question

Here comes the challenge.
Suppose f : Rn → R is differentiable everywhere, and a ∈ Rn is a local maximum for f (i.e. there is a neighbourhood U of a such that f(a) ≥ f(x) for all x ∈ U). Show that Df(a) is the zero row.

Answer 1

@perl @ParthKohli @ganeshie8

Answer 2

I don't understand this ---> "Show that Df(a) is the zero row."

Answer 3

can you elaborate