# Help me solve this matrix please

• Feb 5th 2011, 10:27 AM
elitethut
Help me solve this matrix please
Hi,
I have been trying to solve this matrix for a while now, I don't get what I am doing wrong. I always end up having 2-3 full pages with an ending result that doesn't work at all.

Here is my matrix:
Code:

(2  -1  3  4 | 9)
(1  0 -2  7 | 11)
(3  -3  1  5 | 8)
(2  1  4  4 | 10)

Anyone could help me solve the matrix ?

Thanks so much
• Feb 5th 2011, 11:03 AM
Rabolisk13
When I put in into my calculator, I got an exact answer, so this set of equations is certainly solvable. Can you post your work and we can see where you went wrong, maybe?
• Feb 6th 2011, 04:59 AM
HallsofIvy
I would row reduce each column working from left to right. Here's the first column:
1) Swap the first two rows.
2) Subtract twice the (new) first row from the second row.
3) Subtract three times the (new) first row from the third row.
4) Subtrace twice the (new) first row from the fourth row.

That will give
$\displaystyle \left[\begin{array}{cccc|c}1 & 0 & -2 & 7 & 11 \\ 0 & -1 & 7 & -10 & -13 \\ 0 & -3 & 7 & -9 & -25 \\ 0 & 1 & 8 & -10 & -12\end{array}\right]$.

Can you do the next three columns?
• Feb 7th 2011, 10:08 AM
elitethut
Got it ! Thanks !!