In solving systems of equations, two important forms of matrices are the row echelon form and the reduced row echelon form. Both methods utilize similar row operations, but they aim for different configurations in the matrix. In row echelon form, the matrix is structured with ones along the diagonal and zeros below it, while in reduced row echelon form, the goal is to achieve ones along the diagonal with zeros both above and below the diagonal.
The primary advantage of reduced row echelon form is that once the matrix is in this format, it can be directly converted back into a system of equations without further manipulation. This contrasts with row echelon form, where additional steps, such as substitution, are necessary to find the variable values.
To illustrate the process, consider a matrix represented as follows:
\[\begin{bmatrix}1 & 7 & 14 \\0 & 2 & 4\end{bmatrix}\]
Starting from this matrix in row echelon form, the next step is to manipulate it into reduced row echelon form. This involves performing row operations to eliminate the non-zero entries above the diagonal. Specifically, to eliminate the 7 in the first row, second column, one can add a multiple of the second row to the first row. In this case, multiplying the second row by -7 and adding it to the first row will yield:
\[\begin{bmatrix}1 & 0 & 0 \\0 & 1 & 2\end{bmatrix}\]
After this operation, the matrix is now in reduced row echelon form. When converting this back to a system of equations, it reveals:
- x = 0
- y = 2
This outcome is consistent with the results obtained from the row echelon form, demonstrating that both methods ultimately lead to the same solution.
In summary, while the row echelon form requires less initial work with the matrix, it necessitates additional steps to derive the final variable values. Conversely, reduced row echelon form involves more extensive row operations but simplifies the process of obtaining the solution. This method is often referred to as Gauss-Jordan elimination, distinguishing it from the Gaussian elimination associated with row echelon form.