Question 983143
{{{(matrix(3,4,
1,-1,2,0,
4,1,2,1,
1,1,1,-1))}}}
Replace R2 with 4*R3-R2,
{{{(matrix(3,4,
1,-1,2,0,
0,3,2,-5,
1,1,1,-1))}}}
Replace R3 with R3-R1,
{{{(matrix(3,4,
1,-1,2,0,
0,3,2,-5,
0,2,-1,-1))}}}
Replace R3 with 2*R2-3*R3,
{{{(matrix(3,4,
1,-1,2,0,
0,3,2,-5,
0,0,7,-7))}}}
Replace R2 with 7*R3-2*R2,
{{{(matrix(3,4,
1,-1,2,0,
0,21,0,-21,
0,0,7,-7))}}}
Replace R1 with 21*R1+R2,
{{{(matrix(3,4,
21,0,42,-21,
0,21,0,-21,
0,0,7,-7))}}}
Replace R1 with 6*R3-R1,
{{{(matrix(3,4,
-21,0,0,-21,
0,21,0,-21,
0,0,7,-7))}}}
Divide R1 by (-21), R2 by 21, and R2 by 7.
{{{(matrix(3,4,
1,0,0,1,
0,1,0,-1,
0,0,1,-1))}}}
So,
{{{x[1]=1}}}
{{{x[2]=-1}}}
{{{x[3]=-1}}}