Solution: Here, directly substitute z=x+2y into elliptic paraboloid 2y 2+Z2 = xh to eliminate z, and get: x2+4xy-xh+5y 2 = 0. This is a curved surface, and then find its intersection with plane z=0, so there is the system of equations x 2+4xy-xh+5y.

The curve composed of z=0 is the reference material of the projection curve equation:

Advanced Mathematics, Volume 2, 6th Edition (edited by Mathematics Department of Tongji University)