Surfaces of 3 Variable Question

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Homework Statement



A cone C, with height I and radius I, has its base in
the xz-plane and its vertex on the positive y-axis. Find a
function g(x, y, z) such that C is part of the level surface
g(x, y, z) = 0.

Homework Equations


What would be the formula for the cone such that the base of the cone is lying on the xz-plane and the vertex is on the y-axis?

The Attempt at a Solution


We know that the formula for a cone is x^2+y^2-z^2, but we don't know where to go from there to get the formula for the description above.

Homework Statement


Homework Equations


The Attempt at a Solution

 
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x^2+y^2-z^2 has it's vertex at (0,0,0) and it's axis along the z axis. Your cone has it's vertex at (0,I,0) and axis along the y axis. You'll need to interchange some variables to get the axis right and then shift the vertex up to (0,I,0). Sketch some graphs.
 
There are two things I don't understand about this problem. First, when finding the nth root of a number, there should in theory be n solutions. However, the formula produces n+1 roots. Here is how. The first root is simply ##\left(r\right)^{\left(\frac{1}{n}\right)}##. Then you multiply this first root by n additional expressions given by the formula, as you go through k=0,1,...n-1. So you end up with n+1 roots, which cannot be correct. Let me illustrate what I mean. For this...

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