# Worksheet: Reduced Row Echelon Form

In this worksheet, we will practice identifying the reduced row echelon form of a matrix and using Gauss-Jordan elimination to get it and hence solving a system of linear equations.

**Q7: **

Give the sum of all the pivot entries in the following matrix:

**Q8: **

Describe the row switches which are necessary to put the following matrix into echelon form:

- AWe swap rows 2 and 4, and then rows 2 and 1, and finally rows 2 and 3.
- BWe swap rows 1 and 3, and then rows 2 and 4.
- CWe swap rows 2 and 4, and then rows 1 and 3, and finally rows 2 and 3.
- DWe swap rows 1 and 3, and then rows 2 and 4, and finally rows 3 and 4.
- EThe matrix is already in echelon form; we do not need to swap any rows.

**Q9: **

State whether the following matrix is in echelon form:

- AThe matrix is not in echelon form.
- BThe matrix is in echelon form.