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# Gaussian elimination method watch

1. If you are using this method on a 4x4 matrix and it works out so you get all zeros on the bottom row can you still solve it?

i.e
x1-x2-x3-x4 = y1
x1-x2-x3-x4 = y1
x1-x2-x3-x4 = y1

Also, if you start using similtaneous equations is it wrong. Why?
2. Well, this happens when the matrix does not have full rank, so, either you have no solutions, or you have an infinite number; in the case where you have one row of zeros, you will have one free variable in your solution set.
3. Im still unsure whether there are any answers or not the qu is....

z1 -4z2 +z4 = 12
-3z2 +3z4 = 6
z2 -2z3 +3z4 = 24
2z1 -6z2 -4z3 +8z4 = 72

Can anyone have I go at solving it?
Thanks
4. (Original post by geo3)
Im still unsure whether there are any answers or not the qu is....

z1 -4z2 +z4 = 12
-3z2 +3z4 = 6
z2 -2z3 +3z4 = 24
2z1 -6z2 -4z3 +8z4 = 72

Can anyone have I go at solving it?
Thanks
You might like to play with this applet.

5. ???
6. help???
7. (Original post by geo3)
help???
Did you not understand how to use the applet I gave you a link for.

Enter 4 in the rows/columns box and then enter the coefficients with the answers in the last column. Then hit calculate. You get a complete row of zeroes at the bottom. The implications of this were explained by another poster.

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