Question 10830
don't you realise how tedious matrices are? lol I hate them! I spent YEARS studying at uni doing damn matrices and linear algebra.


Anyway, here are 2 solutions ;-):


1. Gaussian Elimination:
{{{matrix(4,3,
         1, 2, 16, 20,
         3, 6, -1, 23,
         4, 8, 2, 18)}}}


OK, 3 times first row subtracted from second row
and 4 times first row subtracted from third row
gives


{{{matrix(4,3,
         1, 2, 16, 20,
         0, 0, -49, -37,
         0, 0, -62, -62)}}}


Now, third row looks fine..will give z=1, but the second row looks wrong to me. I would go back to the question and check the numbers.


2. cramer's rule:
(look on my Lessons for help on this)
I wont do the working either, as i think your second equation is wrong.


jon.