# Classification of Matrices

I need a little help on solving matrices. I actually just want to confirm my answer

Given matrices :

$$A= \begin{bmatrix} 2 & 0 & 8 & 9 & 7 \\ 0 & 0 & 1 & 2 & 3 \\ 0 & 0 & 0 & 7 & 6 \\ 1 & 0 & 0 & 0 & 9 \\ \end{bmatrix}$$

$$B= \begin{bmatrix} 2 & 0 & 8 & 9 & 7 \\ 0 & 0 & 1 & 2 & 3 \\ 0 & 0 & 0 & 7 & 6 \\ 0 & 0 & 0 & 0 & 9 \\ \end{bmatrix}$$

$$C= \begin{bmatrix} 2 & 0 & 8 & 9 & 7 \\ 0 & 0 & 1 & 2 & 3 \\ 0 & 0 & 0 & 1 & 6 \\ 0 & 0 & 0 & 0 & 1 \\ \end{bmatrix}$$

Which of the following are in reduced row echelon form ?

My answer is all the matrices are not in reduced row echelon form. Matrices B and C are in echelon form, but not matrix A.

Am I correct ?

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There is no need to write "solved" in the title; there is a green indicator on the questions that have an accepted answer. – Zev Chonoles May 29 '13 at 5:21
Thank you Zev Chonoles for telling me that. I usually write SOLVED if the question is answered. Thank again Zev =) – Garett May 29 '13 at 5:23

What's the difference for you between echelon form (E.F.) and reduced E.F. (R.E.F.)? The latter must have $\,1'$s on the main diagonal or what?