How do you graph a three dimensional equation?

Question

How do you plot coordinates on the 3-dimensional coordinate system? And how do you graph an equation, such as z=x^2+y^2?
Thanks in advance.

Answer 1

After setting up the system, you plot the values of z for a pair of x and y.

The given equation is a cone with its vertex at the origin, haaving a circular cross section and axis along the +ve z axis.

Answer 2

http://en.wikipedia.org/wiki/Cartesian_coordinate_system

Theres a picture of a Three-dimensional coordinate system halfway down on that link.(fig 5) Hope that helps, hard to explain when i cant draw a graph on this.