# Thread: How to solve the following systems of equation in matrices/Gauss Jordan form?

1. ## How to solve the following systems of equation in matrices/Gauss Jordan form?

{ -.5x + .5y + .5z = 1.5
4.2x + 2.1y + 2.1z = 0
.2x + ___ + 0.2z = 0

The answer is supposed to be (-1, 1, 1) but i got (10/21, 0, 10/21). I checked my answer by substituting my answer for the variables in the 1st equation and got 3 instead of 1.5.

2. Can you show your work?

Here's how you can do an extended matrix in LaTeX (double-click to see the source code):

$\left[\begin{matrix}0&0&0\\3&1&-4\\4&2&-6\end{matrix}\left|\begin{matrix}-2\\2\\5\end{matrix}\right].$

3. i was able to solve it thru

(5/42)R2 + R1 -> R2
(.5/.2)R3 + R2 -> R3
then
1.5R1 - R2 -> R1
1.5R3 - R2 -> R3
then
R2 - R3 -> R3
then
divide each row by their pivot

thanks for the tip ackbeet.

4. Ok, glad you got it. Have a good one!