What is the gradient ∇f\nabla f∇f of f(x,y)=x2−y2f(x, y) = x^2 - y^2f(x,y)=x2−y2?
⟨2x,−2y⟩\langle 2x, -2y \rangle⟨2x,−2y⟩
⟨x,−y⟩\langle x, -y \rangle⟨x,−y⟩
⟨−2x,2y⟩\langle -2x, 2y \rangle⟨−2x,2y⟩
⟨2x,2y⟩\langle 2x, 2y \rangle⟨2x,2y⟩