Answer Happy

5. (7 pts) Find all directions in which the directional derivative of f(x,y)=ye−xy is 1 at the point (0,2). [ Hint: If u=⟨u1​,u2​⟩ is a unit vector, then u12​+u22​=1; what other relation between u1​ and u2​ does the directional derivative Du​f(0,2) give?]