c. A child's car seat is modelled on the surface = = g(x, y) =2x +6y-. One end of a strap would be at the point P(-1,1,4). 20- 15 i. Find the partial derivatives og and evaluate them at (-1, 1) . ay (3 marks) 11. Find the equation of the plane tangent to the surface at P (2 marks) 111. Calculate the gradient vector Vg at the point (-1,1) . (2 marks) iv. Find the directional derivative Dag(-1,1), where u = 2 3 V13 V13 (2 marks) v. State the direction from (-1,1) for which the surface has maximum slope. (1 mark) vi. State the magnitude of this maximum slope. (1 mark)