YAMT: Matricies

[speg]

Morning all, snowdays rock So i'll spend my day doing schoolwork. Too bad this correspondance is being dumb!

Solve using matrices.
4x -y +z = 2
x - 2y - 3z = 8
3x +y +4z = 6

When I work this out, at the 2nd or third step, I have to bottom row being [0,0,0,48]. Does that not mean 0x+0y+0z=48. Which is obviously not possible. And it's happening on the next two questions too, what am I doing wrong to get these all 0 rows

 

[Reel]

i'm not going to work it out but if you get that condition then it means the equations are conflicting constraints (ie. parallel lines). So, it is possible that you could get it and it just means that that series of equations is unsolvable, has no solution, whatever you want to say.

 

[dullard]

Originally posted by: speg

Solve using matrices.
4x -y +z = 2
x - 2y - 3z = 8
3x +y +4z = 6

Ok add your last two equations:
(x - 2y - 3z) + (3x + y + 4z) = 8 + 6.
The result is,
4x - y + z = 14.
Compare that to your first equation,
4x - y + z = 2,
and you can see that they obviously cannot be both true. Thus there is no answer to your original set of problems. That is why you get a nonsensical equation (0 + 0 + 0 = 48) when trying to solve it.

Note: I don't know which method you are using to solve it, so it is possible that both the problem has no answer and you goofed. But lets just hope that you didn't goof up.

 

[speg]

oopsies, got ahead of myself. Looked in the book and saw "Part B: System of Equations with More Complicated Solutions." Inconsistent systems. Ah well, looks like order has been restored to my mind.

EDIT: So all I have to say once I got 0x+0y+0z=something other 0, is that it's inconsistent and im done? Blarhg! I've been stuck on this lesson for over a week now, and that's all I have to say?!

 

[ryzmah]

Yep, just say it's inconsistent.