Find the gradient of the function f(x,y)=x4−y4f(x,y) = x^4 - y^4f(x,y)=x4−y4 at the point (1,1)(1, 1)(1,1).
⟨4,−4⟩\langle 4, -4 \rangle⟨4,−4⟩
⟨4,4⟩\langle 4, 4 \rangle⟨4,4⟩
⟨1,−1⟩\langle 1, -1 \rangle⟨1,−1⟩
⟨0,0⟩\langle 0, 0 \rangle⟨0,0⟩