Linear Algebra / Gaussian Elimination

In summary, the conversation discusses finding coefficients for the equation of a circle in an xy plane using Gaussian elimination. It is mentioned that there are not enough equations to get a unique solution and that there may be large fractions in the row echelon form. The speaker also confirms that the numbers in the rows will most likely be over 53 and 65.
  • #1
page13
11
0

Homework Statement



Find coefficients a,b,c and d so that the curve of a circle in an xy plane, with points (-4,5), (-2,7) and (4,-3), is given by the equation ax2 + ay2 + bx + cy + d = 0.

Not even sure where to start. Can anyone help me with this?
 
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  • #2
Use Gaussian elimination. Substitute the x and y values for each point into the equation and get three linear equations for a, b, c and d. But you don't have enough equations to get a unique solution. You'll have to express three of those variables in terms of another. You've got to expect this. (ax^2 + ay^2 + bx + cy + d)/k=0 is the same circle for any nonzero k.
 
  • #3
Thanks Dick. I guess I'll get some big ugly fractions in my Row Echelon Form, correct? So far I've got numbers over 53 in the 1st row, over 65 in the 2nd row, and the 3rd row looks like it'll be a 4 digit denominator.
 
  • #4
page13 said:
Thanks Dick. I guess I'll get some big ugly fractions in my Row Echelon Form, correct? So far I've got numbers over 53 in the 1st row, over 65 in the 2nd row, and the 3rd row looks like it'll be a 4 digit denominator.

Probably. I didn't actually work it out, but it doesn't look like it was set up to come out nice. Sounds like you are the right track though.
 

Related to Linear Algebra / Gaussian Elimination

1. What is Linear Algebra?

Linear Algebra is a branch of mathematics that deals with linear equations and their representations in vector spaces. It involves the study of linear transformations, systems of linear equations, and matrices.

2. What is Gaussian Elimination?

Gaussian Elimination is a method used to solve systems of linear equations by transforming them into row-echelon form, making it easier to find the solution. It involves applying elementary row operations to a matrix until it is in its reduced form.

3. What is the purpose of using Gaussian Elimination?

The main purpose of using Gaussian Elimination is to simplify systems of linear equations and make it easier to solve them. It can also be used to find the inverse of a matrix, which is useful in various applications such as solving systems of differential equations and finding the least squares solution to a system of linear equations.

4. What is the difference between a row-echelon form and a reduced row-echelon form?

A row-echelon form is a matrix that has been simplified using Gaussian Elimination, where all leading coefficients are 1 and all entries below leading coefficients are 0. A reduced row-echelon form is a further simplified form where all leading coefficients are 1 and all other entries in the same column are also 0.

5. What are some real-life applications of Linear Algebra and Gaussian Elimination?

Linear Algebra and Gaussian Elimination have various applications in fields such as engineering, physics, economics, and computer science. For example, they can be used to solve systems of equations in circuit analysis, model physical systems in physics, optimize financial portfolios in economics, and perform image processing in computer science.

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