Matrices

[StephenPrivitera]

Solve the system,
x - 2y + 3z - w = 0
-x + 2z + w = 0
2x + y - 2w = 0

The reduced matrix is
1 -2 3 -1 0
0 1 -5/2 0 0
0 0 1 0 0

So, y=z=0
x - w = 0
x=w
right?

Book says no --> x=-w, w arbitrary


...........
This is a very simple but unrelated question. Find the vector equation of the line passing through the points (-1,2) and (3,4). I say (x,y)=(-1,2)+t(4,2)
Book says no --> (x,y)=(-1,2)+t(5,2)
Who's right?

[arcnets]

Originally posted by StephenPrivitera
So, y=z=0
x - w = 0
x=w
right?
I get the same result.

[arcnets]

Originally posted by StephenPrivitera
I say (x,y)=(-1,2)+t(4,2)
Who's right? You are.

[StephenPrivitera]

I guess that's the price you pay for buying the first edition. I'd write the editor, but the book was published in 1986.