need help with the solution for 10and 11

Problem 10. (1 point) Find the point(s) on the surface z? = xy + 1 which are closest to the point (4, 2,0). List points as a comma-separated list, (e.g., (1, 1,-1), (2, 0, -1), (2,0, 3)). Answer(s) submitted: (incorrect) Problem 11. (1 point) Find the volume of the largest rectangular box in the first octant with three faces in the coordinate planes, and one vertex in the plane x + 3y + 6z = 18. Largest volume is Answer(s) submitted