How to know which surface represents equation Q (x,y,z) =0?

In summary, the conversation discusses the equation Q(x,y,z) = -5/2:X2 - y2 + 4z2 + 7xy - 2xz - 2yz and how it can be written in a matrix form. By finding the eigenvalues and eigenvectors of the matrix, the equation can be rewritten in a new coordinate system without mixed terms.
  • #1
starterYEAR
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The equation.
Q(x, y,z) = -5/2:X2 - y2 + 4z2 + 7xy - 2xz - 2yz.

Find its axis and draw its intersection with the plane x + y + z = 0 .
 
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  • #2
Q(x,y,z) can be written as
[tex]\begin{bmatrix}x & y & z \end{bmatrix}\begin{bmatrix}1 & \frac{7}{2} & -1 \\ \frac{7}{2} & -1 & -1 \\ -1 & -1 & 4 \end{bmatrix}\begin{bmatrix}x \\ y \\ z \end{bmatrix}[/tex].
Where I have divided the coefficients of xy, xz, and yz equally to get a symmetric matrix Symmetric matrices always have a "complete set" of independent eigenvectors.

Finding the eigenvalues and eigenvectors of that matrix will allow you to write the equation in a new coordinate system that has no "mixed" terms.
 
  • #3
Misplaced homework question, so I am locking the thread.
 

Related to How to know which surface represents equation Q (x,y,z) =0?

What is the equation Q(x,y,z) = 0 and what does it represent?

The equation Q(x,y,z) = 0 represents a surface in three-dimensional space where the function Q, which is dependent on the variables x, y, and z, is equal to zero. This surface is called the zero-surface or the solution surface.

How do you know which surface represents the equation Q(x,y,z) = 0?

The surface that represents the equation Q(x,y,z) = 0 can be determined by finding the points on the surface where the function Q is equal to zero. These points can be found by solving the equation for one of the variables, such as z, and then plotting the resulting 2D curve in the x-y plane.

What is the role of the variables x, y, and z in the equation Q(x,y,z) = 0?

The variables x, y, and z represent the coordinates of points on the surface that is being described by the equation Q(x,y,z) = 0. These variables determine the location and shape of the surface in three-dimensional space.

What are some methods for visualizing the surface represented by the equation Q(x,y,z) = 0?

One method for visualizing the surface is by plotting the points where the function Q is equal to zero in a 3D graph. Another method is to use computer software, such as 3D modeling programs, to generate a visual representation of the surface. Another option is to create a physical model of the surface using materials such as clay or cardboard.

Can the surface represented by the equation Q(x,y,z) = 0 have more than one representation?

Yes, the surface represented by the equation Q(x,y,z) = 0 can have multiple representations, depending on the values of the variables x, y, and z. These different representations can result in variations in the shape and location of the surface in three-dimensional space.

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