Find a normal vector to the surface x2+y2−z=5x^2 + y^2 - z = 5x2+y2−z=5 at the point (2,1,0)(2, 1, 0)(2,1,0).
⟨4,2,1⟩\langle 4, 2, 1 \rangle⟨4,2,1⟩
⟨4,2,−1⟩\langle 4, 2, -1 \rangle⟨4,2,−1⟩
⟨2,1,−1⟩\langle 2, 1, -1 \rangle⟨2,1,−1⟩
⟨4,1,2⟩\langle 4, 1, 2 \rangle⟨4,1,2⟩