1. The problem statement, all variables and given/known data I'm also having trouble with these: provide the names and sketch the following surfaces: x2+y2+z2=16 x2+y2=9 x2+2y2+4z2=16 z=-√(9-x2-y2) z=√x2+y2 z=x2+y2 2. Relevant equations 3. The attempt at a solution So for the first one it's a sphere with radius of 4, yes? And the second is a circle with radius three. These seem fairly obvious but I'm not sure how to go about visualizing the rest...is this something I just need to pick up on or is there a method I should be using?