This is a problem I got from a Stanford class in calc 3: Let f(x,y,z)=xyz+3. Find an equation of the level surface that passes through the point (1,-2,0). This is as far as I have gotten: The constant for the level surface will be k = xyz + 3 = (1)(-2)(0) + 3 = 3. The equation is thus 3 = xyz + 3, or xyz = 0. From this, I understand that the level surface will consist of the coordinate axes, but is there any way to parametrize or otherwise explicitly define this? If not, should xyz = 0 be sufficient as an equation of the level curve? Thanks!