Question 979553
{{{(matrix(3,6,
6,5,3,1,0,0,
8,4,5,0,1,0,
7,6,3,0,0,1))}}}
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Replace {{{R2}}} with {{{R1*8-R2*6}}} and {{{R3}}} with {{{R1*7-R3*6}}},
{{{(matrix(3,6,
6,5,3,1,0,0,
0,16,-6,8,-6,0,
0,-1,3,7,0,-6))}}}
Replace {{{R3}}} with {{{R2+R3*16}}},
{{{(matrix(3,6,
6,5,3,1,0,0,
0,16,-6,8,-6,0,
0,0,42,120,-6,-96))}}}
Replace {{{R1}}} with {{{16*R1-5*R2}}},
{{{(matrix(3,6,
96,0,78,-24,30,0,
0,16,-6,8,-6,0,
0,0,42,120,-6,-96))}}}
Replace {{{R2}}} with {{{7*R2+R3}}},
{{{(matrix(3,6,
96,0,78,-24,30,0,
0,112,0,176,-48,-96,
0,0,42,120,-6,-96))}}}
Replace {{{R1}}} with {{{7*R1-13*R3}}},
{{{(matrix(3,6,
672,0,0,-1728,288,1248,
0,112,0,176,-48,-96,
0,0,42,120,-6,-96))}}}
So now,
{{{(matrix(3,6,
1,0,0,-1728/372,288/672,1248/672,
0,1,0,176/112,-48/112,-96/112,
0,0,1,120/42,-6/42,-96/42))}}}
Simplifying,
{{{(matrix(3,6,
1,0,0,-18/7,3/7,13/7,
0,1,0,11/7,-3/7,-6/7,
0,0,1,20/7,-1/7,-16/7))}}}
and the inverse is,
{{{(matrix(3,3,
-18/7,3/7,13/7,
11/7,-3/7,-6/7,
20/7,-1/7,-16/7))}}}