Question 903202
Use Cramer's Rule,
{{{A=(matrix(4,4,0,1,1,-2,
                 1,2,-1,0,
                 2,4,1,-3,
                 -2,-4,-7,-1))}}}
{{{abs(A)=30}}}
.
.
{{{A[w]=(matrix(4,4,3,1,1,-2,
                 2,2,-1,0,
                 0,4,1,-3,
                 -19,-4,-7,-1))}}}
{{{abs(A[w])=-321}}}
.
.
{{{A[x]=(matrix(4,4,0,3,1,-2,
                 1,2,-1,0,
                 2,0,1,-3,
                 -2,-19,-7,-1))}}}
{{{abs(A[x])211}}}
.
.
{{{A[y]=(matrix(4,4,0,1,3,-2,
                 1,2,2,0,
                 2,4,0,-3,
                 -2,-4,-19,-1))}}}
{{{abs(A[y])=41}}}
.
.
{{{A[z]=(matrix(4,4,0,1,1,3,
                 1,2,-1,2,
                 2,4,1,0,
                 -2,-4,-7,-19))}}}
{{{abs(A[z])=81}}}
.
.
{{{w=abs(A[w])/abs(A)=-321/30}}}
.
.
{{{x=abs(A[x])/abs(A)=211/30}}}
.
.
{{{y=abs(A[y])/abs(A)=41/30}}}
.
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{{{z=abs(A[z])/abs(A)=81/30=27/10}}}