graphing problem? how do you graph equation that has x y z as variables?

Question

Find the intercepts and symmetry.
Please teach me how to sketch the graph. is there some website out there that could graph equation like this?

1. x^2 + y^2 - 8z = 8
2. x^2 = (9 - y^2)(9 - z^2)

Answer 1

You can graph it in the x,y plane as level lines giving z different values
In this case 1) represents Cf. with center (0,0) and radius
8+8z.
You can do the same for 2)
x^2/(9-z^2) +y^2=9 which for any -3>z<3 are elipses
and forI zI>3 hyperboles
For z=+- 3 directly you get x=0

Answer 2

You need to graph in three dimensions - the solution is a surface.