The answer keeps being 17, even as x and y both get vanishingly close to zero.
I encourage you to play around with a 3D graphing calculator and see all the different paths you can take along that surface to reach the singularity. They all "reach" it at different heights.
I encourage you to play around with a 3D graphing calculator and see all the different paths you can take along that surface to reach the singularity. They all "reach" it at different heights.