Gaussian Elimination

Description: Gaussian Elimination is a method for solving systems of linear equations by using elementary row operations to transform the system into an equivalent system that is easier to solve.
Number of Questions: 15
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Tags: linear algebra gaussian elimination elementary row operations
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What is the first step in Gaussian elimination?

  1. Find the leading coefficient in the first column.

  2. Subtract the first row from the other rows.

  3. Multiply the first row by a constant.

  4. Divide the first row by a constant.


Correct Option: A
Explanation:

The first step in Gaussian elimination is to find the leading coefficient in the first column. The leading coefficient is the first nonzero entry in the column, starting from the top.

What is an elementary row operation?

  1. Adding a multiple of one row to another row.

  2. Multiplying a row by a nonzero constant.

  3. Swapping two rows.

  4. All of the above.


Correct Option: D
Explanation:

Elementary row operations are operations that can be performed on a matrix without changing the solution set of the corresponding system of linear equations. The three elementary row operations are adding a multiple of one row to another row, multiplying a row by a nonzero constant, and swapping two rows.

What is the goal of Gaussian elimination?

  1. To transform the system into an equivalent system that is easier to solve.

  2. To find the solution to the system of linear equations.

  3. To find the determinant of the matrix.

  4. To find the eigenvalues of the matrix.


Correct Option: A
Explanation:

The goal of Gaussian elimination is to transform the system of linear equations into an equivalent system that is easier to solve. This is done by using elementary row operations to eliminate variables and reduce the system to a triangular form.

What is a triangular form?

  1. A matrix in which all the entries below the main diagonal are zero.

  2. A matrix in which all the entries above the main diagonal are zero.

  3. A matrix in which all the entries on the main diagonal are nonzero.

  4. A matrix in which all the entries off the main diagonal are zero.


Correct Option: A
Explanation:

A triangular form is a matrix in which all the entries below the main diagonal are zero. This means that the system of linear equations can be solved by back-substitution, starting from the last equation.

What is back-substitution?

  1. A method for solving a system of linear equations by starting from the last equation and working backwards.

  2. A method for solving a system of linear equations by starting from the first equation and working forwards.

  3. A method for finding the determinant of a matrix.

  4. A method for finding the eigenvalues of a matrix.


Correct Option: A
Explanation:

Back-substitution is a method for solving a system of linear equations by starting from the last equation and working backwards. In each step, the value of one variable is found in terms of the values of the other variables, and then this value is substituted into the previous equation. This process is repeated until all the variables have been found.

What is the advantage of using Gaussian elimination to solve systems of linear equations?

  1. It is a systematic and efficient method.

  2. It can be used to solve systems of any size.

  3. It can be used to find the solution to a system of linear equations even if the system is inconsistent.

  4. All of the above.


Correct Option: D
Explanation:

Gaussian elimination is a systematic and efficient method for solving systems of linear equations. It can be used to solve systems of any size, and it can be used to find the solution to a system of linear equations even if the system is inconsistent.

What is the disadvantage of using Gaussian elimination to solve systems of linear equations?

  1. It can be computationally expensive for large systems.

  2. It can be difficult to keep track of the row operations.

  3. It can be difficult to find the solution to a system of linear equations if the system is inconsistent.

  4. All of the above.


Correct Option: A
Explanation:

The disadvantage of using Gaussian elimination to solve systems of linear equations is that it can be computationally expensive for large systems. This is because the number of row operations required to solve a system of linear equations grows with the size of the system.

What are some other methods for solving systems of linear equations?

  1. Cramer's rule

  2. LU decomposition

  3. Jacobi iteration

  4. Gauss-Seidel iteration


Correct Option:
Explanation:

There are many other methods for solving systems of linear equations, including Cramer's rule, LU decomposition, Jacobi iteration, and Gauss-Seidel iteration.

Which method is best for solving a particular system of linear equations?

  1. It depends on the size of the system.

  2. It depends on the structure of the matrix.

  3. It depends on the desired accuracy.

  4. All of the above.


Correct Option: D
Explanation:

The best method for solving a particular system of linear equations depends on the size of the system, the structure of the matrix, and the desired accuracy.

Gaussian elimination can be used to find the determinant of a matrix.

  1. True

  2. False


Correct Option: A
Explanation:

Gaussian elimination can be used to find the determinant of a matrix by reducing the matrix to an upper triangular form. The determinant of an upper triangular matrix is the product of the entries on the main diagonal.

Gaussian elimination can be used to find the eigenvalues of a matrix.

  1. True

  2. False


Correct Option: B
Explanation:

Gaussian elimination cannot be used to find the eigenvalues of a matrix. The eigenvalues of a matrix can be found using other methods, such as the power method or the QR algorithm.

Gaussian elimination is a numerical method.

  1. True

  2. False


Correct Option: B
Explanation:

Gaussian elimination is an exact method. This means that it will always find the exact solution to a system of linear equations, if a solution exists.

Gaussian elimination can be used to solve systems of nonlinear equations.

  1. True

  2. False


Correct Option: B
Explanation:

Gaussian elimination can only be used to solve systems of linear equations. To solve systems of nonlinear equations, other methods, such as the Newton-Raphson method, must be used.

Gaussian elimination is a widely used method for solving systems of linear equations.

  1. True

  2. False


Correct Option: A
Explanation:

Gaussian elimination is a widely used method for solving systems of linear equations because it is a systematic and efficient method that can be used to solve systems of any size.

Gaussian elimination is the only method for solving systems of linear equations.

  1. True

  2. False


Correct Option: B
Explanation:

Gaussian elimination is not the only method for solving systems of linear equations. There are many other methods, such as Cramer's rule, LU decomposition, Jacobi iteration, and Gauss-Seidel iteration.

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