Help with math Matrices problem

1. Sep 18, 2007

ThomasHW

1. The problem statement, all variables and given/known data
Find the reduced row echelon form of the following matrix:

$$\begin{array}{c}\ \\ \\ \end{array}\;\begin{vmatrix}\;-4 & 0 & 4\;\\\;2 & -4 & 1\\\;-4 & 4 & -2\end{vmatrix}$$

3. The attempt at a solution
$$\begin{array}{c}\ \\ \\ \end{array}\;\begin{vmatrix}\;1 & 0 & 1\;\\\;0 & 1 & \frac{1}{4}\\\;0 & 0 & 1\end{vmatrix}$$

I've tried it a few times and keep getting that answer. I've inputted that answer and it's wrong. Am I supposed to keep reducing the third row (even though those are constants?)

2. Sep 18, 2007

dontdisturbmycircles

Look at your last row. It says 0x+0y=1 (Assuming this is an augmented matrix)

3. Sep 19, 2007

ThomasHW

I figured it out. I was supposed to make the 1 and 1/4 in the third row zero's as well.

4. Sep 19, 2007

HallsofIvy

Staff Emeritus
Yes, what you showed was "row echelon" form. "Reduced row echelon reduces above the diagonal also. Actually, untill you get down to a row all 0s you will have just the identity matrix.

5. Sep 19, 2007

ThomasHW

I had assumed not to touch the last row because that is usually the row of constants. In this case it wasn't - I had just assumed it was.