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Topic: Help with linear System
Replies: 2   Last Post: Jul 12, 1996 9:13 PM

 Messages: [ Previous | Next ]
 Eric Jonas Posts: 1 Registered: 12/12/04
Help with linear System
Posted: Jul 7, 1996 3:32 PM

Help!!!!!!
I have been given a problem which I have reduced to the following
linear system:

z+w=102
x+y=129
z+y=75
w+x=156

Now, I want to solve. But every time I try to use substitution, I
don't get anywhere. So, I figured on trying to set it up as a matrix,
and solving using Cramer's Rule. But the matrix:

1 0 0 1
0 1 1 0
0 0 1 1
1 1 0 0

Has a determinant of 0, which my math book says results in no or
infinant many solutions. So, as I last resourt, I entered it into my
HP48's linear system solver. It (for those who aren't farmiliar with
the HP48) asks for a coefficient's matrix, a constant matrix, and then
spits back the solution in matrix form: [52 104 25 50]. My question
is:
HOW DID IT ARRIVE AT THIS ANSWER?
I would think that it would utilize Cramer's rule and determinants,
except that the determinant of the coefficient matrix is zero. Anyone
know how the heck the HP48 solved this, or know of another method
which I might be able to try to help me arrive at the correct answer?
...Eric Jonas
eric-j@primenet.com
P.S. Could you also please e-mail
me any information you discover? My ISP's
news server has been experiencing difficulties
over the past several days, and I don't want
to miss any information which might point
me in the right direction.

Date Subject Author
7/7/96 Eric Jonas
7/8/96 John P. Becker
7/12/96 edew@netcom.com