# Thread: having trouble imaganing this graph

1. ## having trouble imaganing this graph

in a 3d space
a shape which is created by x=y y=0 z=0
and z=4-x^2

specially the last one i dont know what is z=4-x^2

2. ## Re: having trouble imaganing this graph

Originally Posted by transgalactic
in a 3d space
a shape which is created by x=y y=0 z=0
and z=4-x^2

specially the last one i dont know what is z=4-x^2
Take any value for y. For example y=0. Then z=4-x^2 represents a parabola in the plane y=0 with vertex (0,0,4). Hope you can sketch this parabola. Now take another value for y. Say y=1. Then you have another parabola with the same shape (vertex at (0,1,4)) but on the y=1 plane. Likewise we can choose any value for y. So this represents a parabolic surface,with the vertex as the y axis.

3. ## Re: having trouble imaganing this graph

the attached photo is not appearing could you post a link?

4. ## Re: having trouble imaganing this graph

Originally Posted by transgalactic
the attached photo is not appearing could you post a link?
Strange. I can see it. But anyway here I have attached it again as a pdf.