Find a unit vector perpendicular to the surface o(x, y, =) = xy'22 =4, at the point (-1, -1, 2). Remember: . If you need to enter a vector, enter an ordered list of components, so for A you can enter either A = (Ars Ay: Az) = {Ar, Ay: Azi . Note that the system isn't great with multiplying through by overall factors, so it's better not to write e.g. ? (2Ar: 2Ay: 2Az) . . Remember NOT to evaluate square roots numerically. If you need V2, type it using the calc pad (under operations) or by typing 'sqrt'. . Also remember that your tutorial has Hints in it, at the end of each chapter. If you're stuck, they are often quite useful! A vector perpendicular to the surface $ = 4 at (-1, -1, 2) is