## Can you reverse row operations?

At the beginning of the section, we mentioned that every elementary row operation can be reversed. Since elementary row operations correspond to elementary matrices, the reverse of an operation (which is also an elementary row operation) should correspond to an elementary matrix, as well.

**What are the row operations?**

There are three types of matrix row operations: interchanging 2 rows, multiplying a row, and adding/subtracting a row with another.

**What are the three types of row operations?**

The three elementary row operations are: (Row Swap) Exchange any two rows. (Scalar Multiplication) Multiply any row by a constant. (Row Sum) Add a multiple of one row to another row.

### What are row replacement operations?

ReplacementEdit Replace one row by the sum of itself and a multiple of another row. A more common paraphrase of row replacement is “Add to one row a multiple of another row.”

**What makes a matrix Elementary?**

1: Elementary Matrices and Row Operations. Let E be an n×n matrix. Then E is an elementary matrix if it is the result of applying one row operation to the n×n identity matrix In. Those which involve switching rows of the identity matrix are called permutation matrices.

**How do you perform a row operation?**

How To: Given an augmented matrix, perform row operations to achieve row-echelon form. The first equation should have a leading coefficient of 1. Interchange rows or multiply by a constant, if necessary. Use row operations to obtain zeros down the first column below the first entry of 1.

#### What is back substitution?

Mathwords: Back-Substitution. The process of solving a linear system of equations that has been transformed into row-echelon form or reduced row-echelon form. The last equation is solved first, then the next-to-last, etc.

**Does det AB det A det B?**

If A and B are n × n matrices, then det(AB) = (detA)(detB). In other words, the determinant of a product of two matrices is just the product of the deter- minants.

**Does row replacement change eigenvalues?**

A row replacement operation on A does not change the eigenvalues.