Help with math Matrices problem

  • Thread starter ThomasHW
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In summary, the conversation discusses trying to find the reduced row echelon form of a given matrix. The attempt at a solution is shown and it is found that the last row should also be reduced to complete the process. The conversation ends with a realization that the last row was not just a row of constants.
  • #1
ThomasHW
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Homework Statement


Find the reduced row echelon form of the following matrix:

[tex]
\begin{array}{c}\ \\ \\ \end{array}\;\begin{vmatrix}\;-4 & 0 & 4\;\\\;2 & -4 & 1\\\;-4 & 4 & -2\end{vmatrix}
[/tex]

The Attempt at a Solution


[tex]
\begin{array}{c}\ \\ \\ \end{array}\;\begin{vmatrix}\;1 & 0 & 1\;\\\;0 & 1 & \frac{1}{4}\\\;0 & 0 & 1\end{vmatrix}
[/tex]

I've tried it a few times and keep getting that answer. I've inputted that answer and it's wrong. Am I supposed to keep reducing the third row (even though those are constants?)
 
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  • #2
Look at your last row. It says 0x+0y=1 (Assuming this is an augmented matrix)
 
  • #3
I figured it out. I was supposed to make the 1 and 1/4 in the third row zero's as well.
 
  • #4
Yes, what you showed was "row echelon" form. "Reduced row echelon reduces above the diagonal also. Actually, until you get down to a row all 0s you will have just the identity matrix.
 
  • #5
I had assumed not to touch the last row because that is usually the row of constants. In this case it wasn't - I had just assumed it was. :cool:
 

FAQ: Help with math Matrices problem

What is a matrix?

A matrix is a rectangular array of numbers, symbols, or expressions arranged in rows and columns. It is often used to represent a set of linear equations or to perform operations such as addition, subtraction, and multiplication.

How do I add or subtract matrices?

To add or subtract matrices, they must have the same number of rows and columns. Simply add or subtract the corresponding elements in each matrix to create a new matrix.

How do I multiply matrices?

To multiply matrices, the number of columns in the first matrix must match the number of rows in the second matrix. Then, multiply each element in the corresponding row of the first matrix by each element in the corresponding column of the second matrix and add the products together to get the corresponding element in the new matrix.

What is the identity matrix?

The identity matrix is a square matrix with 1s on the main diagonal and 0s everywhere else. When multiplied by another matrix, the identity matrix acts as the "identity" element, leaving the other matrix unchanged.

How do I find the inverse of a matrix?

The inverse of a matrix is a matrix that, when multiplied by the original matrix, results in the identity matrix. To find the inverse, use the matrix inverse formula or use row operations to convert the original matrix into the identity matrix.

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