Answer Happy

True or False, please explain.
(e) Let f(x,y,z)=xy−ln(z). Then ∇f(x,y,z)=⟨y,x,−z1​⟩. (f) Let f(x,y) be any function of two variables. We can always find global extreama for f. 1 (g) Let f(x,y) be any function of two variables. The local extreama always occur at critical points.