Graphing a level surface f(x,y,x)=c

In summary: But it's not necessary, because you can also visualize the equation in other ways. For example, if you know that the equation is in the form x^2 + y^2 = z^2, then you can see that the surface is a square if z = 0, a trapezoid if z = 1, and an ellipse if z > 1.In summary, the graph of the equation x2 + (1/4)y2 - z = 1 is a surface that can be graphed in three dimensions, but interpretation of information is difficult.
  • #1
bfusco
128
1

Homework Statement


sketch the graph f(x,y,z)=x2 + (1/4)y2 - z, c=1

The Attempt at a Solution


while i don't expect anyone to be able to graph it for me for i think obvious reasons, i have no idea how to interpret any of the information given to even attempt a graph.

usually i would try to figure out how it looks in an 2d x,y plane and add the z dimension, but i can't do that with this. please help
 
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  • #2
bfusco said:

Homework Statement


sketch the graph f(x,y,z)=x2 + (1/4)y2 - z, c=1

The Attempt at a Solution


while i don't expect anyone to be able to graph it for me for i think obvious reasons, i have no idea how to interpret any of the information given to even attempt a graph.

usually i would try to figure out how it looks in an 2d x,y plane and add the z dimension, but i can't do that with this. please help

Graph the surface x2 + (1/4)y2 - z = 1 in three dimensions.
 
  • #3
Mark44 said:
Graph the surface x2 + (1/4)y2 - z = 1 in three dimensions.

yea i don't know how, is what I am saying. i even tried to look online for a 3d grapher that would allow for inputs of f(x,y,z) but i couldn't find any, so is there any way to interpret the info from the equation. like in the x direction is the graph x^2, in the y direction does it look like the graph x/4..etc?
 
Last edited:
  • #4
Have you spent any time sketching graphs of quadric surfaces?

The thing to do in this problem is to recognize what sorts of shapes you get in various planes, not axes. For example, plane z = 0 intersects the surface in an ellipse. In other words, the cross section of the surface in the x-y plane is the ellipse x^2 + (1/4)y^2 = 1.
In the plane z = -1, the cross section is the graph of the equation x^2 + (1/4)y^2 = 0, which is a degenerate ellipse that consists of only a single point.

In other planes that are parallel to the x-y plane, you get different ellipses.

In the x-z plane (where y = 0) what shape do you get?

In the y-z plane (where x = 0) what shape do you get?

If you get a few cross sections at various places, you can start to get an idea of what the overall surface looks like.
 
  • #5
bfusco said:
yea i don't know how, is what I am saying. i even tried to look online for a 3d grapher that would allow for inputs of f(x,y,z) but i couldn't find any, so is there any way to interpret the info from the equation. like in the x direction is the graph x^2, in the y direction does it look like the graph x/4..etc?

You could solve your equation for z to get it in the form z = g(x,y) if that's what your 3d grapher needs.
 

1. What is a level surface?

A level surface is a three-dimensional representation of a function in which all points on the surface have the same output value, or "level". In other words, it is a surface where the function is constant.

2. How do you graph a level surface?

To graph a level surface, you first need to choose a value for the output, or "level", that you want the surface to represent. Then, you can use a graphing tool or software to plot the points where the function equals that output value. These points will form the surface of the level surface.

3. What information can be obtained from a level surface?

A level surface can provide information about the behavior of a function in three dimensions. It can show how the function changes as the input values vary, and can also help identify critical points, such as maxima and minima, on the surface.

4. Can a level surface be graphed for any type of function?

Yes, a level surface can be graphed for any function that takes in multiple inputs and produces a single output. This includes functions with two or three independent variables, such as f(x,y) or f(x,y,z).

5. How can level surfaces be useful in scientific research?

Level surfaces can be useful in visualizing and understanding complex functions in three dimensions, which is important in various fields of science such as physics, chemistry, and engineering. They can also aid in solving optimization and modeling problems.

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