Lecture: Matrix row-reduction

At 2 minutes in the lecture, this matrix is described as being in row echelon form because it has 1s in the main diagonal and 0s underneath:

Why is this matrix shown as being in row echelon form?

Lecture: Matrix row-reduction

At 2 minutes in the lecture, this matrix is described as being in row echelon form because it has 1s in the main diagonal and 0s underneath:

Why is this matrix shown as being in row echelon form?

Luis said both are row echelon form which means that being an upper diagonal matrix with 1s in the diagonal is only a sufficient but not a necessary condition.

This wikipedia definition will fit the two cases in your question (and cases of less equations than variables).

Cheers!

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