Identify the row operation

Oct 13, 2025 by wbrum.org 17 views

Introduction

In linear algebra, matrices are used to represent systems of equations and perform various operations on them. One of the fundamental operations in matrix algebra is row operations, which involve modifying the rows of a matrix to obtain a new matrix that represents the same system of equations. In this article, we will perform a specific row operation on a given matrix and write the new matrix.

The Original Matrix

The original matrix is given by:

\left[ \begin{array}{rrrr|r} 1 & 1 & 1 & -1 & 4 \\ 0 & 1 & -8 & -9 & 0 \\ 2 & 0 & 3 & 3 & 12 \\ 5 & 4 & 3 & -6 & 9 \end{array} \right]

Row Operation: -2 R_1 + R_3

The row operation we will perform is -2 R_1 + R_3, which involves multiplying the first row by -2 and adding the result to the third row. This operation is denoted by the following notation:

-2 R_1 + R_3

To perform this operation, we will first multiply the first row by -2, which gives us:

-2 \left[ \begin{array}{rrrr|r} 1 & 1 & 1 & -1 & 4 \\ \end{array} \right] = \left[ \begin{array}{rrrr|r} -2 & -2 & -2 & 2 & -8 \\ \end{array} \right]

Next, we will add the result to the third row:

\left[ \begin{array}{rrrr|r} -2 & -2 & -2 & 2 & -8 \\ \end{array} \right] + \left[ \begin{array}{rrrr|r} 2 & 0 & 3 & 3 & 12 \\ \end{array} \right] = \left[ \begin{array}{rrrr|r} 0 & -2 & 1 & 5 & 4 \\ \end{array} \right]

The New Matrix

The new matrix obtained after performing the row operation -2 R_1 + R_3 is:

\left[ \begin{array}{rrrr|r} 1 & 1 & 1 & -1 & 4 \\ 0 & 1 & -8 & -9 & 0 \\ 0 & -2 & 1 & 5 & 4 \\ 5 & 4 & 3 & -6 & 9 \end{array} \right]

Discussion

Row operations are an essential tool in linear algebra, and they can be used to solve systems of equations, find the inverse of a matrix, and perform other operations. In this article, we performed a specific row operation on a given matrix and wrote the new matrix. The row operation -2 R_1 + R_3 involved multiplying the first row by -2 and adding the result to the third row.

Conclusion

In conclusion, row operations are a powerful tool in linear algebra, and they can be used to modify the rows of a matrix to obtain a new matrix that represents the same system of equations. By performing row operations, we can solve systems of equations, find the inverse of a matrix, and perform other operations. In this article, we performed a specific row operation on a given matrix and wrote the new matrix.

Future Work

In future work, we can explore other row operations and their applications in linear algebra. We can also investigate the use of row operations in solving systems of equations and finding the inverse of a matrix.

References

[1] Hoffman, K., & Kunze, R. (1971). Linear Algebra. Prentice-Hall.
[2] Strang, G. (1988). Linear Algebra and Its Applications. Academic Press.

Appendix

The following is the original matrix in a more readable format:

1	1	1	-1	4
0	1	-8	-9	0
2	0	3	3	12
5	4	3	-6	9

The new matrix obtained after performing the row operation -2 R_1 + R_3 is:

1	1	1	-1	4
0	1	-8	-9	0
0	-2	1	5	4
5	4	3	-6	9

Q: What is a row operation?

A: A row operation is a mathematical operation that involves modifying the rows of a matrix to obtain a new matrix that represents the same system of equations.

Q: What are the different types of row operations?

A: There are three main types of row operations:

Row Switching: Switching two rows of a matrix.
Row Multiplication: Multiplying a row of a matrix by a non-zero scalar.
Row Addition: Adding a multiple of one row to another row.

Q: How do I perform a row operation?

A: To perform a row operation, you need to follow these steps:

Identify the row operation: Determine the type of row operation you want to perform (row switching, row multiplication, or row addition).
Apply the operation: Perform the row operation on the matrix.
Verify the result: Check that the resulting matrix represents the same system of equations as the original matrix.

Q: What are some common row operations?

A: Some common row operations include:

R_1 + R_2: Adding the first row to the second row.
-2 R_1 + R_3: Multiplying the first row by -2 and adding the result to the third row.
R_1 + 3 R_2: Adding three times the second row to the first row.

Q: How do I know if a row operation is valid?

A: A row operation is valid if it does not result in a matrix that represents a different system of equations. To check if a row operation is valid, you can:

Check the row rank: Make sure that the row rank of the matrix does not change after the row operation.
Check the column rank: Make sure that the column rank of the matrix does not change after the row operation.
Check the determinant: Make sure that the determinant of the matrix does not change after the row operation.

Q: Can I perform multiple row operations in a single step?

A: Yes, you can perform multiple row operations in a single step. However, you need to make sure that the row operations are valid and do not result in a matrix that represents a different system of equations.

Q: How do I use row operations to solve a system of equations?

A: To use row operations to solve a system of equations, you can:

Transform the matrix: Use row operations to transform the matrix into a form that is easier to solve.
Eliminate variables: Use row operations to eliminate variables from the matrix.
Solve for the variables: Use row operations to solve for the variables in the matrix.

Q: What are some common applications of row operations?

A: Some common applications of row operations include:

Solving systems of equations: Row operations can be used to solve systems of linear equations.
Finding the inverse of a matrix: Row operations can be used to find the inverse of a matrix.
Determining the rank of a matrix: Row operations can be used to determine the rank of a matrix.

Q: Can I use row operations on a matrix with complex entries?

A: Yes, you can use row operations on a matrix with complex entries. However, you need to make sure that the row operations are valid and do not result in a matrix that represents a different system of equations.

Q: How do I know if a row operation is reversible?

A: A row operation is reversible if it can be undone by another row operation. To check if a row operation is reversible, you can:

Check if the row operation is invertible: Make sure that the row operation is invertible, meaning that it can be undone by another row operation.
Check if the row operation is reversible: Make sure that the row operation is reversible, meaning that it can be undone by another row operation.

Q: Can I use row operations on a matrix with non-square dimensions?

A: Yes, you can use row operations on a matrix with non-square dimensions. However, you need to make sure that the row operations are valid and do not result in a matrix that represents a different system of equations.