Question

What is the row echelon form of a `4xx4` matrix?

Answer 1

A matrix is in row echelon form if

1. All nonzero rows are above any rows of all zeroes. In other words, if there exists a zero row then it must be at the bottom of the matrix.

2. The leading coefficient (the first nonzero number from the left) of a nonzero row is always strictly to the right of the leading coefficient of the row above it.

3. All entries in a column below a leading entry are zeroes.

An example of 4x4 row echelon form would be
[1 0 0 0
0 1 0 0
0 0 1 0
0 0 0 1]

Note that there are infinitely way of writing a matrix in a row echelon form.