Find the surface area of the part of the plane z = 4 + 3x + 7y that lies above the rectangle [0, 6] x [0, 6].

Find the point on the plane 8x – y + 8z = 80 nearest the origin. (х, у, z)

Find a plane that is perpendicular to the two planes x + y = 3 andX + 2y - Z = 4.

Find the point in which the line through the origin perpendicular to the plane 2x - y - z = 4 and meets the plane 3x – 5y + 2z = 6.