Answer
Elliptical paraboloid
Work Step by Step
Comparing to Table 12.1, we recognize the form of an Elliptical paraboloid (with y and z interchanged; y is negative).
This means that it opens along the y-axis (instead of the z-axis),
and the minus tells us that it opens in the -y direction.
The cross sections with $x=k$ and $z=k$, are parabolas,
and with $y= -k$ they are circles (special cases of parabolas).
