Find the directional derivative of f(x,y)=x2−y2f(x, y) = x^2 - y^2f(x,y)=x2−y2 at (1,1)(1, 1)(1,1) in the direction of u=⟨1/2,1/2⟩\mathbf{u} = \langle 1/\sqrt{2}, 1/\sqrt{2} \rangleu=⟨1/2,1/2⟩.
000
111
2\sqrt{2}2
222